Question for artists

I recently purchased a re-hauled mask. After looking at some of the screen shots I’ve noticed a few minor things that I would like to tweek, mainly just definition to some of the cracks to make them stand out more. What type and color paint should I use for the cracks around the eyes and cheeks. Also, how should I apply it and do I need to seal it afterwards. Again, I’m talking minor tweaks so I’m wondering if a sealant is even necessary. Also, I’m unsure whether or not the original owner/artist used a sealant to cover the paint job (can’t get a hold of them to find out). I assume this would affect the type of paint I used for touch-ups? Thanks!

Wt