Hi! Thanks for the message, though I apologize in my lateness on answering.
You absolutely have not missed your experimental stage, nor have you shot past the mark where it’s too late to learn. It is never too late to learn. A good place to start is Youtube. There is a whole community devoted to helping the average person become a colourful glamazon. Watch beauties like vintageortacky, goldiestarling, nikkietutorials. You will, with practice, be able to hone and shape your own style by watching them, I promise.
As far as supplies, invest in a few key brushes, namely for the eye area. ELF has a really cool little brush kit that’s perfect for beginners and is also easy on the wallet (x).
Makeup brands-you do not have to buy from the department store to get a good product. Revlon is one of the best brands I know and you can find it in just about any drugstore or Walmart. And Loreal’s HIP eyeshadows are among some of my favourite. I actually have every available shade, that’s how much I love the product. And shop indie! Brands like Glamour Doll Eyes, Concrete Minerals, Rockeresque Beauty, and Sugarpill are reputable and quality without putting a dent in your savings.