04 Jun 10 3:17 am
Realistically, this guy is probably looking for something for nothing. But if he's really a customer he doesn't know what the hell he wants and even if he did he would be incapable of communicating it to you. You'll have to do what's called a "requirements analysis", basically that's just figuring out what he wants. It's a systematic question and answer process (bring plenty of visual aids and coffee). If you're not familiar with that already you've got some homework to do.
Quote him a price of about $100 to $300 for just that and then you will know what you will need to do from there and you'll be able to give him a bid/quote for the job you've both agreed he wants done. By the way, his reaction to this will provide you with insight into what he really thinks your time is worth.
If it's still a go then break his payments to you over certain parts of your work. For example, paying you a small amount in advance to deliver a prototype/sketch up of what you've both agreed he wants. Then after you both agree you're on the right track he should pay you for the next stage of the work which you will then do.
Get collaboration and agreement each step of the way before proceeding to the next stage of work. Never let him tell you to just go ahead and do it. You want him to "own it".
Put everything in writing and HAVE HIM SIGN OFF ON IT IN ADVANCE. NO EXCEPTIONS. EVER. PERIOD. When he changes his mind, "forgets" what he previously told you or just bails on you at least you'll have been paid for your time and effort.
Keep a precise record of all your work and your communications with him in case you ever have to prove you acted in good faith. Good luck.