I used rose art color pencils. I want to know what colors to use for skin tones?

It depends on the skin tone you are going for. I normally just fiddle around on some scrap paper first. Try mixing pinks and peaches, use light browns to make it darker and yellows can help lighten it, but you have to be careful with yellow. Orange can benefit you too. Spend some time just trying different ways to layer it, eventually you will know what the colors do together and will be able to know what colors will work well with pink and what ones wont.