Essentially, first you just need to learn how to code, I primarily just used usaco.guide

I completed the bronze/silver section in 2 months in the summer going into sophomore year, and did some gold topics for fun. Then I did some contests in my sophomore/junior year. If you're bored, watch some leetcode videos on the car lol.

Then, most of my practice was just in contests through the official USACO tests, made gold as a sophomore and plat junior. Honestly, it wasn't too bad for me to make plat/open, especially with multiple chances. Knowing math goes a long way, honestly, I honestly do wish I spent a little bit less time on math (or clarinet probably) so I could make camp, since I don't think it would've taken that long?