I also tend to play townie sims in accordance to their bios. It gives me some form of direction to take them. And for some families that are really popular, I try to build up any generally ignored family members, and focus on them.
Making brand new sims, unless I have a firm idea in mind for their backgrounds, they all are normal skin toned POCs in general, mixed in particular. If I had to guess why, I'd say because if I'm going to spend any time looking at characters, I should be able to see myself in them, which I don't really get in mainstream media without it being gross. And even then, when I do make an occult sim that has an odd skin color (like anything on the rainbow slider), I mix them up in CAS with a few generations of realistic skin tones so that it looks more naturally occurring, if that makes sense.
When I play a new file, I'll start with one sim, female, and randomize a few traits and play. I always try to achieve their lifetime wish. Most of my sims are artists or cooks because if I leave them alone, someone goes for the paint so might as well stick with it and Cooking because they have to eat more than mac and cheese. I've started on gardening and fishing now.
I'm slowly moving away from default clothes because a lot of my sims have similar clothing choices and it's grating to see several sims in the same exact outfit. Also, female sims tend to wear a lot of shorts because I make them wear boots more often than not and The Sims 3 doesn't allow pants to tuck in, which is one of the main things I was happy about in the previews for The Sims 4.
If I have the male sim and it looks right on them, they get facial hair. All the guys are hairy from the neck down once they hit Young Adult. My female sims don't get long hair very often and their busts stay within reasonable sizes.
I used to make all my sims with a slightly square head, but I'm currently practicing with round faces. It's kinda weird trying to match the face to the rest of their body. None of my sims are really skinny, they tend on average for their lifestyles, but I have had fat sims slim down because they ran everywhere not far enough to drive
I'm also trying to explore other towns but I keep defaulting to Moonlight Falls, Midnight Hollow, and Bridgeport; Sunset Valley if they're moving out of those three towns.