Step One: Get Engaged. It's preferable to plan this several months in advance by actually buying a ring and not just casually mentioning it as a hypothetical.
Step One Dash B: Remind your best friend to take it slow because he's now BEHIND you... but not like that.
Step Two: Ask her. No, really. Make sure you get a solid "yes" to this part.
Step Three: Keep it a secret from everyone but your family... and said best friend... and work. Oh, and your friends. Oh wait, and also your managerial posse. Icarus probably won't notice.
Step Four: Work really long, hard hours right before a big event so that you look like the midnight dream pixies beat you with a meat hammer and then go to the races to fraternize with the natives. Let your newly engaged best girl show off her bling this time, unlike the last time when she was only pretending on Twitter and freaked people out.
Step Five: Go back home only to find that your douchebag "friends" are throwing you an engagement party complete with condom balloons.