On the software side of things. Primatte, Commotion Pro and I think Ultimatte as well all give you the option to first clean up your green screen. This option is key, I have shot against some terribly lit green screens and had them come out looking picture perfect once I used the screen correction software.

With that in mind I now mostly look for creating a good contrast between the subject and the screen. Any hot spots on your subject are going to be harder to cut. I also found that keeping light levels from the foreground and the background about the same helps alot.

I'm building a home made green screen with ply wood and spray paint right now.
You have all mentioned different types of software to use for keying... is there any real disadvantage to just using the green screen effect in Final Cut Pro?