1. I use a washable marker, dab off the excess, and go over the nipples with eye shadow. Same for lips but with lipstick.
2. Personally, I like to use powder makeup and fix it with vaseline. Apply the makeup with a small brush or makeup applicator then dab a tiny bit of vaseline into the nipple and carefully rub it in (TPE dolls only). After leaving to dry, I find the color lasts for a few months or more. Lipstick is best applied with a small makeup brush and once dry clear lip gloss can be applied to give it a shine.
3. If you want glossy lips, you can mix a little clear lip gloss with the lipstick on the brush or applicator.