If you're taking photos on which you intend to change or replace the background, you might think that a blue or green screen would be best to shoot against. That's the "traditional" way, right? But actually, it's a bad idea. That colour bleeds into hair, and around edges, and it's a replacement nightmare.
This is the order of your options:
BEST: Shoot against the actual colour you want in the photo - no editing necessary.
NEXT BEST: Shoot against a colour which is very similar to the colour you eventually want - minimal editing necessary.
MIGHT BE OK: Shoot against a dark neutral colour if your subject has light hair, or a light neutral colour if your subject has dark hair - the
natural contrast will help you replace the colour in editing, but can still be tricky. (Example)
BAD: Shoot against green or blue (or any other bright colour, really).
VERY BAD: Shoot against a mixed/busy background.