http://vote.individualpreference.info/ - excellent website on each candidate's stance/track record/electoral promises on a particular area e.g Foreign Policy etc. You can pick and rank the items most important to you and it gives a final score of the politicians + items you picked and how closely they match your criteria.
I was speaking to a colleague of mine, a professor in political sociology and he said people tend to vote by tradition and emotion and not rational choice. But it is better to know and go in with open eyes and vote than to ignore the facts and vote blindly no?