When it comes to wardrobes I tend to have each sim have a signature colour or 2, as well as a style (goth, nerdy, casual etc) and make all their outfits fit that. I usually choose their style based on personality/job etc.
Sims without the Collector aspiration might still collect something in particular (loves animals so collects frogs/fish/aliens/insects or is a hippy into collecting crystals), or different items that go together (collectables and buy mode items that have a matching theme, like cityscape paintings & city themed snowglobes, or map and globes etc. for the veteran traveller).
I let sims choose their own friends/enemies/lovers by letting them be autonomous (I do have extra autonomy mods in too) and following Whims.
I have a mod in that randomises traits on each birthday instead of showing the trait/aspiration picker (you could also do this with external randomisers though).
I lock 5 random skills for CAS-created sims when I first play them (YA/teen) and 5 more when they reach adult age. For born in game they get randomised and locked at toddler/teen/adult birthdays. I might unlock a locked skill in elderhood as a rediscovered hobby etc. (This requires mods). This ensures that all sims I play have different abilities and may have to consider career/hobby choices from a more limited pool of options etc.
(E.G. Sim A has cooking looked, but not baking, so they use that as their main form of sustanance. Sim B has logic locked, so putting them in the science career is a terrible idea, but you can still do it for the lols if you want.)
