There have been some articles and discussions lately about making your game more easy for color-blind players to use, and that is of particular importance to me since I am red-green color-blind. It is very annoying to play a game and have to keep asking, "What color is that?" when simple changes to the design could have avoided this trouble. And since around 10% of males are color-blind, this is a not insignificant amount of players for your game.
1. Use symbols in addition to colors to identify things if possible. So, if there are different resources printed on cards and referenced by color, use a symbol as well. If it is physical components, you can have them be different shapes.
2. Brighter colors are easier to distinguish than darker colors. So you might want to de-saturate your colors for mood, but don't. Saturate them for ease of seeing.
3. Test your game with color-blind people. If they have to ask "what's this, what's that color?" then you need to work on it some more.
4. It can be hard to choose a set of colors for the different player colors such that there are no conflicts for color-blind players. For me, a player color set of black, white, yellow, blue, and red is about the best you can get. Brown is a terrible color since it has all the colors mixed into it, it can change appearance in different ways for differently color-blind people. Of course, for someone who is completely color-blind (which is rarer than the other kinds), even these sets won't work, so you might have to invent a different system.
5. Test your game in low light with non-color blind people. Color is harder to see the less light there is, and if you play in low-light and can't tell the colors apart, it will for sure be impossible for someone who is color-blind.