Green screens are useful for video because you can just apply a colour key (which removes any of the selected range of green). For photos though, Any solid colour will work since you're going to have to go in manually and touch up the edges on whatever kind of mask you use. The 'magic select' tool is the devil. Don't use it, or if you have to, don't use it without modifying your selection to feather at least one or two pixels, otherwise you'll end up with a really sharp edge.
If you're absolutely set on using a screen though, Flash Blitzen has the right of it: the screen and the model need to be lit separately, (to avoid a nasty green glow that's a pain to deal with) and the model should be a fair bit ahead of the screen. If they model is wearing shiny things, like a polished plastic armor or metal bracer/crown, then the green is going to show up there too. The photog probably will as well.
All in all, Try white, black or grey for still photography, that way the reflections and 'glow' won't be so awful.
~Misadventures in costume making~
======= In Progress =======
Kureha - Shining Wind: 10% (drafting)
Khaleesi - A Song of Ice and Fire: 80% (wig and finishing)