Staying out of the sun is absolutely #1. The difference between my skin as an Arizona transplant who is still mostly nocturnal and the skin of someone who has lived here their whole life and spends more time outdoors is extreme! I don't go out here for even a few minutes without SPF.
I've only just turned 40, and don't really have many age-related skin complaints just yet. I'm mostly doing my best to keep my skin and body hydrated. I do use the The Ordinary's Argireline for forehead creases. They weren't actually bad to begin with, I'm just vain, but now they're pretty much completely invisible.
Besides that, I use glycolic acid or lactic acid every 2-3 days to keep my cells turning over (currently between brands--currently I'm using up this The Ordinary one, but it makes me feel sticky), and then just Cerave, sometimes with a few drops of some kind of oil if my skin is particularly dry. The type of oil doesn't seem to matter a ton, so I'm just going through a backlog of subscription box stuff. Right now it's a buzzword-filled Cannalogica Facial Hydration Oil with Full Spectrum Hemp Extract blah blah blah.
I've had conflicting diagnoses, but I do have some sort of skin condition, probably eczema/rosacea. I use azelaic acid if it happens to flare up on my face, which seems to help with the redness. Amlactin (12% lactic acid) usually works for the rest of my body, if things aren't bad enough to resort to my steroid cream prescription. I'd use it every day, but it smells funky and I'm just lazy, because I'm also needing to cover the entire surface of my skin with SPF.
I'm currently looking for a new, inexpensive oil cleanser, since the Julep one that worked for me no longer really exists. At least I managed to grab a bunch of them on clearance at Target, so I have a few months left! Other types of cleansers leave my skin too dry.