Happy Sunday!

I apologise if this has been asked before but I need some guidance regarding skins, overlays, masks etc. Basically my laptop decided to die so I had to buy a new one and I'm starting fresh with downloading CC. I've never been that clued up on them and just downloaded them in the past without knowing the difference. I've noticed makeup doesn't always work with certain ones. Basically if anyone has some sort of guide or tutorial to understanding them all that would be amazing. I'm using this time in isolation to up my sims 4 knowledge so I can get more out of my games.

Thank You!