Here is a brief excerpt from Steve Poland’s blog. Be sure to subscribe to his RSS feed–good stuff!
Evaluating ideas — talk to people; tell them your idea; what problem does it solve. Great if it solves a problem you personally have — because then you know a need exists [if you didn't find a solution already in all your research]. Start small and ugly. Don’t go into debt — 1 in 100 ideas that are executed actually become something.