I just got asked a common question of budding entrepreneurs looking to begin a Web start-up.

"I have this idea, and I've been thinking about working on a start-up. What do you think?"

The quick answer is, "I don't know."
"But here is something that I wish I had followed":

1. Ignore people who don't get your idea right away. The fact is - even you might not "get it" at the start either. Probably a lot of "gut" feeling in your idea at the moment.
2. Focus on getting the quickest nastiest prototype out quickly. Don't over design it. Think days/weeks - not months.
3. See if people like your prototype, and "get it" once they see it and use it.
4. If they get it "clean it up - just a bit" so that you can give it out to more people - the target audience. Make sure that these testers, are not just people you know. You want unbiased opinion and experience.
5. Do people get it? Are people using it? Do people want it to do more (not different) things? (If yes for 2/3 then keep at it, else back to the drawing board.) You should have clear evidence that reinforces your "gut" that you are on to something special.

I am not certain that these 5 steps are appropriate for EVERY Web start-up, but I believe that whatever you do, your first goal should be to figure out if your idea is worth pursuing at all. Do this before you invest too much of your time and money, and especially before you ask anyone else to spend their time and money on your idea.