You want something that is a very muted, pale blue or green. The best I've found in Kryolan is a light gray-blue color: G83
. Keep in mind that your own skintone may influence how the color appears on your own skin. You can always buy smaller cakes of colors to mix in and create the perfect tone for your skin. If you have a Kryolan store in your area, you will be able to test the colors on-site. If not, then you can try smaller cakes to check the color before committing to a large size.
To help with oil, use alcohol on cotton balls to clear the oil from the surface of your skin and create a clear foundation for your body paint. Apply the paint with a sponge or brush and allow it to dry. Mist a light application of fixier spray all over the body paint. Some websites suggest misting fixier spray into the paint before applying it to help keep it in place longer, and others suggest ONLY using fixier spray (I have not personally tried the "only fixier" route). Additionally, you can use any sort of translucent finishing powder over the body paint and fixier spray to help control oil. Whatever you do, make sure you take a flash photo of your body paint to make sure the powder won't reflect light if you do use it.