How do I get better at CS:GO?

Well, first make sure you have a hardware you're confident in.

I had a cheap keyboard and a weak 15 "gaming" mice, then I swapped to a Deathadder Elite mouse and a Blackwidow V2 keyboard, and it's like changing from one world to another. Just with those new peripherals, my aim improved a lot just by having a better grip on my mouse and keyboard, and also having a much more precise mouse captor.

Then you just need to use aim maps or softwares, because I saw some old Call of Duty pros go on CS:GO and rank up to Global Elite just by having 99% of aim and 1% of gamesense.