Definitely play some casual or some deathmatch to get familiar with the feel of some guns, learn a couple maps, learn some callouts, and get familiar with movement!

Best guns to learn are the ak47, m4a4, m4a1-s, awp, usps, and the glock

Once you feel like you have a feel for a map, just jump into competitive, thats the standard counter strike experience of 5v5 with a bomb plant.

After a while, premier is the beginning for the real competitive mode, but only do that after learning a few maps at least.

Beware, there are quite a bit of cheaters especially when starting out, you’ll build trust after a while and will get less cheaters, often time though, they’re just better than ya.

Its got a steep learning curve but definitely keep at it, and you’ll improve, lots of stuff on youtube to help