A good way to start would be to replace products you're currently using. I started off by finding a new cleanser and moisturizer. Two things! Not overwhelming. Just with that I had amazing results already. My western cleanser was too drying and I hated my moisturizer so I never moisturized. Awful awful mistake.
Look for an oil cleanser and foaming cleanser. There are a lot of recommendations in the sidebar and holy grail lists. Be careful because we do have a huge hype train here haha. Pick a recommendation that is best suited for your skin type, not popularity.
I am 23 and have oily/combo skin, am prone to occasional acne breakouts and started off with Boscia because I could pick it up at Sephora. The cleansers are pricy at $28 but last me about 4-5 months on average. I use makeup breakup as my oil cleanser and follow with detoxifying black cleanser. I'm pretty sure Sephora carries trial-sized Boscia. I've been using Boscia for over a year now and it's great! My sebum production went down significantly and skin cleared up.
Ulta and Target carry Hada Labo Tokyo. I saw a post recently that Target carries a trial kit for cheap you can try out for Hada Labo. Start there maybe, while you check out products and samples.
After integrating cleanser and moisturizer, look at sunscreen. If you prefer local, there are Tony Moly and The Face Shop physical locations in the States. A lot of Asian populated areas with Asian grocers will carry some items as well.
You'll need to learn to be very patient since online orders will be shipping from Korea and will take like a month to arrive. Many online shops sell samples. As easy as it is to jump on the hype train and want to order full size of a miracle product hoping it will work for you, don't. Be patient!
As for acne and sebum, chemical exfoliants are highly recommended. Western chemical exfoliants are pretty decent, and you will find Paula's Choice recommended here quite often as well as over in /r/skincareaddiction.
I just placed an order myself for samples of AHA and BHA lotions and gels and moisturizers from Paula's Choice.
An AHA will help with surface exfoliating and moisturizing. Examples of AHA are lactic acid, glycolic acid. BHA is a misnomer that refers to salicylic acid which is great at combatting acne (because salicylic acid doesn't actually have the chemical structure of a beta hydroxy acid). BHA can be drying.
Start there: cleansers and moisturizer. Look into sunscreens and AHA and or BHA you want to incorporate next to help with acne. Take your time with the other stuff. As always constantly ask questions. Everyone here is nice and helpful!
edit For redness I've heard of Avène from the place I get facials done at. It's a western brand but expensive. I hear a lot about their thermal waters. Not sure what your budget it but thought I'd mention them.