For the most part I usually just try to find a good balance between what I like for aesthetic purposes and the stat increases I get. This is likely not a terribly unique approach, but I usually have one outfit that I select that's predominantly for looks, but hopefully fits the character type with relevant stat bonuses to at least some degree (basically just means less switching gear around - especially now with all the layered armor.)
And then I'll pick something else for running around and dungeon-crawling that's a little more stat-based. I try to free myself up a little bit to experiment and not worry so much about the appearance. For instance, I rarely wear full-face headgear (because I just like being able to see my character's face,) but sometimes the stat boost is too much to overlook. So I'll just take the helmet off when I'm in a town or expecting to be doing a lot of dialog. Kind of ditto with glasses and hats, too - I'll wear a silly hat if I'm raiding a dungeon and it's got boosts I really want.
I still don't have a ton of time spent with Fallout 4 - a lot of this is just based on how I've approached past Bethesda games. I've been doing the "two outfits" approach for a few installments now. Hopefully someone will make a mod that will make saving outfits a little bit easier (even right now it feels like the organization is not great or easy to dig through to figure out which sort of Leather Left Arm I want or already have equipped.)
At the start I really liked the Drifter outfit - it was the most sensible thing I could find early on that looked appropriate to the character. I couldn't really find anything to go as a "base layer" for a little bit that I was happy with or gave me a good stat boost. So when I found the Army Helmet I thought it was a good fit for the bump in armor rating:
https://photos.google.com/share/AF1QipMwS_7c-X25docEEs243R0u9kF0qFi00v-YlJEgNBMhUwG5VdHdmONQfW4TKwiT_Q/photo/AF1QipPmiULEQhjblAMWH9UR89qFzW5VYpgIho8lttD9?key=N1VpTVZVSzBUUlFLa1RsRW90QXRON3NocjdZSFRB
https://photos.google.com/share/AF1QipOUt5JVsncdKuqeR2N5YgBqInpiAiX_4lzzzHC0Lxbp7EwaOpo43nUVsM5zfEAPrw/photo/AF1QipOv6KQ7zCVMNnjmNYtTltTS8Up06WyseD5AsO8R?key=bUdxZTRvTzdGcExPd3FieEo4VzVoRjhaRnhqMXBn
A little later I've switched to flannel and jeans with a few armor layers that I've upgraded - significantly more armor rating now. I'm still keeping an eye out for some base layer clothing, and hoarding anything I thought would be neat. And I usually ditch the helmet when I'm somewhere I expect to be doing a lot of talking (and primarily just for sheer roleplaying purposes.)
https://photos.google.com/share/AF1QipPQHKBNaPQ4VR4OK7GTaot6HzfGEBw9or9AQS7RLbEZHfrdJ0o45LqfnolnzNk1xw/photo/AF1QipNa6guDRklzxflqvx-XFHj5bB5KEnVPgUEWcX39?key=RUNpTmkxbWJMWEtPRjB2sixaTW05STNZMnl1MzF3