hi, so I've been looking for tutorials for a long time on how to do this because I'm really interested in it. could anyone give me some pointers, or link me to a tutorial on it? thank you.

here are skin overlays/masks made by other people for an idea of what i'm talking about.
they are often found in the "skin details" section in CAS.

http://www.thesimsresource.com/arti...s-i/id/1259107/
http://modthesims.info/download.php?t=541542

edit: I've pretty much painted what I want to use as my overlay, but I've no idea how to get it in-game. And do I need to paint it in black and white, or in colors? thanks

I usually make overlays to work as wrinkles, so I do them in black and white. It depends on the kind of overlay you want. The easiest way IMO (since you seem to be pretty noobie at creating cc for TS4), is using Sims 4 Studio. Just clone some skin detail (as I said wrinkles work better for me) and import your texture. You'll see if it fits so you can make the changes you need before trying it in-game. Save it and you're pretty much done

adsfjdaskf thank you so much for responding <3 I suppose i'll use S4S for this kinda stuff then.
and yes, I'm very noobie to making cc.