I think what you meant to say was:
"But ideas in and of themselves are worthless until you patent them and sell them to patent trolls"

I typically will charge like 1/2 up-front and 1/2 at the end. If you plan on doing that make sure you include in your contract an expiration time of your original quote. I've had customers that paid their initial fee then we didn't hear from the client or get any content from them. 2 years later they call and want the same service at the quoted rate. Since then I have increased my rates twice and have stopped doing those little projects. Because we didn't put a expiration on that quote we are stuck doing this at a much lower rate. Thankfully it is a very simple site.