I am not an expert on such things, however, based on my exploration, reading and observation I offer the following suggestions - you can use any or all of them according to your time and budget allocations.
- Branding, pricing Like in the real world before you sell anything work out your branding and market positioning. Do you want to become an exclusive brand? Mid range? or 'home brand'. Once you've worked out what market you want to appeal to you need to ensure your prices and image (packaging, store, location, etc) are targeted at this audience. You may choose to have more than one brand for different markets. Whatever you do, make sure your shop or brand name appears on all product names/descriptions; is included in the landmark you put with your products, etc.
- Let friends and aquaintances know you've set up shop. This is probably the most obvious - and the cheapest form of promotion. Let people on your friends list and the people you spend time with in-world know you have a shop. Your friends are going to want to see you succeed and are likely to spread the word to others. It's a good idea to drop them a clearly named landmark and/or notecard to make it easier for them to share with others.
- Freebies, dollarbies, lucky chairs, mob boards. These are all tools used to attract people to your store - and have them tell others about your store. The trick is to provide a freebie that is the same quality as the items you sell. This gives people an idea of what to expect from your products - and hopefully makes them want to buy more of them. If you give away or sell cheaply sub-standard or lower quality products you are probably not going to inspire people to buy. Less is more - and make sure it's quality. If the items is particulary good, it's likely people will tell their friends - and possibly blog about it; share on social networks and/or post pictures on the Internet. If you give a substandard item - they may blog about that too... but it's likely to be negative press. One quality freebie will attract more - and better - attention that boxes full of junk. Freebies obviously are items you just give away for free. Dollarbies are items you sell cheaply - generally for a dollar but it may be another smaller amount. Lucky chairs and mob boards are tools you purchase with the idea of attracting a crowd - or at least getting people to your store. In the case of lucky chairs, people often call their friends in when their friends 'letter comes up - and mob vendor boards lower the price according to the number of people around. I've also see barter boards where you haggle with the board to strike a deal. Top designers do this - many of them have items freely available at 'the free dove'. They also often create items for big events, charity events or holidays to give away. Give the same customer service to people who make enquiries or who obtain your freebies and dollarbies. They may have paid less but if they get good polite/helpful service are more likely to think well of you and return. You can also make your give-aways and dollarbies available on SL online shopping sites for extra exposure.
- in-world advertising board rental - there are many venues in-world with advertising boards you can rent. In most cases you should have a picture, a notecard and possibly a landmark on hand. Ensure that any notecard you prepare has a landmark embedded (just drag and drop your landmark to the notecard to embed it. You can embed notecards, images, landmarks, scripts and objects in notecards depending on their pemissions). Most advertising boards work in this way. Pay the board, touch - get a menu, CTRL + drag and drop your items on to the board (ensure they are named as per the instruction notecard you were given). Touch board again to activate. The trick with these boards is to ensure they are in a high traffic area and in a place where the kinds of people that might buy your goods are likely to be. I've used these boards once and I scouted each area carefully and then started with one board in each selected location, monitored them carefully over the week and then let some boards expire and added additional boards elsewhere. This has a cost attached and the more popular the area, the more expensive the boards are likely to be. It's often a bit hit and miss, so would not be the first thing I'd recognise.
- advertising by blog - a number of second life bloggers either sell advertising or else spend their time blogging about in world products. A quick search of google will help you find the bloggers that write about the kind of items you sell. Contact the bloggers in-world (check their profile before IM'ing or sending anything as they may have rules or guidelines about how you contact them). Give them one of your products for free - they may tell others. Buying advertising has a cost attached... and varying degrees of success. Getting a popular blogger to tell others about your products in oen of their posts may mean giving something away but can bring huge returns. A list of Second Life Bloggers be found in the Second Life Blogger group on ning.com.
- blogging and social networks self promote! Tell people about what you are doing, how you made it and how long it took. Tell them about new stuff you've released and what you find interesting. Depending on your time, energy and will to partipate you can do this via a traditional blog (eg. blogger, wordpress, livejournal, typepad, tumblr, etc); via a micro-blog/forum where you only post short messages equivalent to a text message (generally 140 characters). Microblogging sites include twitter (a focus on broadcasting/informing and information gathering), plurk (plurk works like a mini forum), brightkite and hundreds of others. If you are really tricky you can site up to many and update them all at once using a tool like ping.fm. You hate writing? No drama. A picture tells a thousand words (when accompanied by a SLURL/in-world teleport link and shop name). Post pictures of your products on image sharing sites like flickr, google's picasa web albums, etc. If you join flickr, there are also lots of special interest second life groups that you can share your pictures with - creating further awarness of you and your product. You can also do video product demos using sites such as YouTube, etc. As well as promoting your product - you are likely to meet some great people, find some great places, spaces and projects and make some new friends/acquaintances this way. You'll also hear a lot more generally about what's going on in and around Second Life and related virtual environments.
- Second Life(tm) classified ads Open Search (bottom of your viewer window), go to classifieds, select place an ad. Last time I did this you nominated an amount you wished to pay - and obviously those who pay the most, get placed higher. If you are going to use classifieds, I recommend that you think carefully and make sure you categorise your ad appropriately. The commerical classifieds are always full - and often with a lot of junk. I'm not sure this is the best way to share information but it's not totally hopeless either. Advertise and pay at your own risk.
- hold an opening, sale... or fashion show - you may hold this at your store... or at a rented venue. If you are going to have an event it's worth looking around and investing in some entertainment (getting a well known and popular DJ or musician is recommended as they often let people know where they are playing) and some prizes and/or give-aways. Make sure any products incude a landmark - and make sure they include your store or brand name. Those who don't buy today may come back tomorrow... or next week... or next month. An event can be a more expensive exercise so plan it well and think carefully before you do it. Sometimes it's better to wait a little rather than rush in and find you should have done a number of things differently. Before you hold your event, I recommend attending a range of events held by others... it'll give you a good idea about what people expect... and will help you work out the kinds of things you MUST do and decide what you can do differently that others didn't do.
- Gifting It's a great idea to have a way that people can offer your products as gifts. If you generally sell your products copy/no tranfer, consider making a version that is transfer/no copy... or else making your goods available on a site or through vendors that enable people to gift goods to another avatar.
- Online shopping XStreetSL.com (formerly SL Exchange (SLX)), OnRez.com and Apez.biz are all sites that allow you to sell your goods via a website (the purchaser or an avatar they gift items to via this site will receive the goods in-world. When you sell your goods on these sites a commission may be deducted for goods over a certain price as a fee for the privilege. You can give away freebies or sell your dollarbies via some or all of these sites - which is another great way to promote yourself. Some sellers increase the prices of goods on these sites to cover the commission - if I'm buying a more expensive item I often check if it's available more cheaply in world. In some cases sellers will make the item cheaper on the site. There is no hard and fast rules. If you do sell your goods on these sites it's useful to include the SLURL of your store/s in the product description/information. It's also useful to have 'signs' in your store that link customers straight to your seller profile on these sites.
- Gift cards If you are flush, you can purchase a gift card system. The best I've seen is the TMC system which does not come cheaply (it's cheaper if three businesses get together and purchase it at once). This is the system you'll see in use at Blaze, Insolence and a range of other stores. It allows you to choose a store and value... and your friend/gift recipient to choose goods to suit their own style. You pay... they shop. If you don't want the expense of purchasing this system you can do what Jeepers Creepers does... or used to do. Sell a non-copyable object that is the gift card and provide a notecard with instructions. The shopper finds the item they want, IM's you and sends you their gift card - in exchange, you give them their purchase via an inventory transfer. This method works, but requires a lot more input from you ... where as the TMC system is fully automated.
- Packaging/labelling People will moan a lot if they get something that didn't turn out to be what they expected. Either make sure the packaging provides all of the information; or that they have access to a notecard or some form of more information. At the very least tell them about the permissions on the object (and if it is no modify but has a resize script in it... tell them that). The more you tell them before purchase, the more likely you are to meet or exceed their expecations.
- demos and holo rezzers/vendors Many stores ofter demos which often come with ugly attachments so people won't swipe your stuff. Demos are a great way of getting an idea about how something will look/fit. The biggest bitch I've heard about skins and shoe demos is that they should not cost anything - they should be free. Again, it's up to you. In terms of furniture, houses, etc - some stores either make 'display homes' / 'display rooms' availble where people can inspect the goods... or where prims are limited, may use holo vendors or temporary/semi-permanent rezzers to allow customers to rez or look at the object... which will disappear/be cleaned up after a certain time.
- rental/commissioned space, expos Some shops rent spaces in popular shopping precincts in world or at special events in order to promote their goods. Often these stores have a prim limit of 25-50 prim so generally are used to show case your best selling products and often contain a landmark giver and/or sign that will direct people back to your main store. Along the same lines there are some spaces that will allow you to use the space in return for a commission of your sales. In terms of special events there are a number of big expos that take place in world each year.
- get involved in sim or grid-wide treasure hunts Treasure hunts have become a bit of a manic craze on the grid. Often a sim, mall or collective of stores will set up a treasure hunt trail together. This is a good way of getting people to your store. Even if they don't stay, if they pick up your freebie on the hunt and like it, there's a good chance they'll return - don't forget to include a landmark and notecard in with your freebie. And ensure your product is properly labelled.
- fishing and other crazes Get a 7Seas fishing set up... or alternative type of set up that will attract visitors. People went a bit crazy trying to find unique fish and trading them as collectables... there's a range of things like this... if you can host a fishing hole and/or competitions you may attact extra visitors. Please note - this is an added extra you offer... it's not guaranteed to bring people milling to your shop - so think carefully about it (and about prim allocation) before you implement something like this.
There's probably a million and one other things you can do - but this list should give you some starting points. Most of all, look around, talk to others, read a few blogs ... and learn as you go.