Any theatrical lighting store will be able to sell you a color swatchbook to that you can browse to select your gel colors. Amber and red family gels often have lower transmission loss while still yielding rich colors. We would often put two front fill fixtures on the same dimmer channel with complementary gel colors instead of matching the gels. This gave the performers a bit more depth and made it look like we had more lights than we actually did. Also some colors work better together than others, be prepared to experiment a little until you get your color scheme right.
White light is an effect.
Don't overuse it and it can be a very effective tool, especially in a backlight situation. Most spotlights should be a bright color, but a nice bastard amber or rose can be much more flattering on skin tones than pure white which tends to make Anglo complexions look sallow. A couple of other tips. Any light mounted lower than eye level is going to cause garish shadows on your face. This can be a useful effect, but generally it's a bad idea.