Like many others have said, I don't usually touch the genetics, as in the things you can't even change without cheats, except when a couple has too many children that look too much alike, but with my playstyle, that doesn't happen often. There's also the issue that one of my mods (although I don't know which one, or why) causes some born-in-game or randomly generated sims to look like this with their mouths closed:
https://abload.de/img/mundjgck2.jpg
Sometimes I keep it, but usually not. When I change the hair colour (either because I want unnatural hair colours that children can't be born with, or to simulate a phase, etc.), I often imply that it's dyed by leaving the eyebrow and/or facial hair in the original colour. I may sometimes add or remove body hair, well, the latter most of the time, because ever since we got body hair, every other random female sim tends to spawn with it.
Oh, and of course I always create their outfits, or use the premade styles when I'm not feeling creative. You can't trust the game with properly clothing sims, especially if you're using cc, because you'll end up with something like this:
https://abload.de/img/cascef7z.jpg
