How to paint a silicone doll: darken nipples, paint the anus, lips, add freckles, etc.
TEMPORARY
Apply normal makeup, such as waterproof eye shadows. After your look is done, use a big makeup brush and apply cornstarch. This will help to seal it. This should last a few weeks.
PERMANENT
TO DARKEN NIPPLES AND ANUS:
Get any eyeshadow palette you like: https://www.amazon.com/s?k=eyeshadow+palette
Get a silicone adhesive sealant: https://spartanlover.com/products/clear-rtv-silicone-adhesive-sealant-3-oz
Mix a little of the makeup with a little of sealant in a waxed paper cup. Apply it to the areolas.
FOR OTHER PAINTING PROJECTS:
Get a clear silicone base: https://spartanlover.com/products/platinum-silicone-paint-base-8-ounce-kit
Get a set of pigments: https://spartanlover.com/products/color-pigments-for-silicone-9-pack
Get a solvent if you intend to paint a large area or if you need thin out the paint: https://www.brickintheyard.com/products/sam-oss-silicone-solvent
Watch this guide: https://www.youtube.com/watch?v=IjloBWSDdWw