Ok, so I've just started working on tatooed skins as well. Pretty funny thing and I'm getting better at photoshop with this
Very early version of Yakuza tattoo(just one arm and upper chest). Still base skin tone, so don't look for any changes here. Making all skin tones is 30minutes of work anyway.
Looks pretty messed up at long distances but I think it will do after adding more colour/burning it a bit.
But slavers got the tatoo! It would be cool to actually know who is a slaver, by just looking at the guys head! It would also make sense to add the reputation drop to those who shoot slaver players.
I believe most people will have hair so you wouldn't see anything at all
Edit: After looking at tribal guys in normal fallout I've started to burn muscles a little more. They will be much better visible from distance(Much closer to original)