I'm with you. I'm partially color blind and partially color stupid. I have a tough time but have learned to get pretty good at it by doing a couple things better.

1. Pay attention! When you shoot mark the shot well and pay close attention to what you see the deer run past and mentally mark that stuff too.
2. When he is out of site Listen! As best you can. You'd be surprised what you can figure out by listening. Many times you'll confirm these things by tracking later from your visual marks.
3. Use a gun or bow that make dang big holes! I love my slug gun. My Blackpowder load is a slower 100 gr TC 250 gr balistic tip that hammers them harder than the slug. THe more blood the better your chance of seeing it.
4. Don't forget that a lot of sign is not on the ground. Watch for hair and blood on the sides of trees and in the underbrush. Also get used to noticing turned up leaves and ground where the deer went instead of just looking for color.