Color blindness is estimated to affect up to 10% of the population, making many popular games difficult to play because one player cannot distinguish between red and green meeples. Designing your game components with accessibility in mind can go a long way towards making sure everyone can enjoy your game.
It's simple; just put some thought into the colors you pick for the same pieces (black, white, red, and blue are recommended, while pieces that are blue and yellow or red, green, and brown are not). You can also consider using differing sizes or colors with symbols (red star, green square, blue circle) to help differentiate your pieces and make your game more accessible.
To determine how your game colors appear with color blindness, input them into an online color blindness simulator.