I think a lot about what I would tell my younger self if I could. Being trans does that to you. One thing I would make sure to include is a guide to skincare; I think it was kind of a pointless waste of time figuring this stuff out. So here's what I know and what I use. I'm not getting any money from this page.
I care about the following things:
I have deferred learning the minutae of what specific cosmetic additives are slowly killing us. I instead use the Yuka Android app. You can scan barcodes or search products and it tells you if there's anything to worry about for the ingredients. I often will double check it if it says "watch out for this one!" because it can get overzealous.
You want something to clean your face. This cleanser should be PH-balanced for skin - make sure it actually says the PH, or you can find someone who's tested it. It should not leave your skin feeling tight or dry after application. I have settled on the Holifrog Tashmoo Hydrating Water Lily Milky Wash. It's expensive, but it lasts so much longer than you'd think.
You should only touch your face with clean hands. I keep my cleanser halfway in the shower, and usually use it then. You wet your face, do 1 pump of the cleanser, and rub it in circles all over using your hands. Then rinse it off. Don't dry your face, just let it air dry. Washcloths are too harsh.
Tretinoin is a very effective anti-aging, anti-acne medication. It's been around for a long time so we understand the safety profile pretty well. You want as high of a concentration as you can stand. You need to work up to this; I started with The Ordinary's retinoid serum, then got prescription tretinoin, then increased the dose. You apply just a pea sized amount - first every few days, working up to once a night. Put it on once your skin is dry. Read the package insert. The best way to get this in the US is to go to a dermatologist, though grey market stuff is pretty cheap too.
This is the most important item. Wait like 2 minutes for the tret to soak in, then apply this. I use Good Molecules' Lightweight Daily Moisturizer. It's really good, not greasy at all, and quite cheap.
Every day you're outside for more than 15 minutes, apply facial sunscreen. Probably every day but that is more of a best practice. This is the most important thing for reducing photoaging. It also significantly mitigates skin cancer risk - the most preventable cancer! You generally want a Korean brand, because they've got better active ingredients over there. The FDA has been dragging its heels on approving new ones. I use the Goodal Heartleaf Calming Moisture Sun Cream. The "mineral based sunscreen" health concerns are overblown; a high-SPF sunscreen you use consistently is going to be better for your health (preventing cancer) than an annoying low-SPF zinc one. I don't have a body sunscreen I like yet. Write me with one?
Morning: Moisturizer, sunscreen. Evening: Cleanser, tretinoin, moisturizer.