How to train properly in CSGO?

Could you recommend me some routines?

Well you need to play some training maps or play alot on some map for long time like office for example

one thing that can help is AimLab, a "game" to train valorant aiming, cs:go, r6, and more

Workshop has alot of AIM training maps, you should start there.

i spent years doing ffa hs only servers for hours on end... unfortunately i used dust 2 only servers so i only ever win dust 11

Well you can try AimLabs or using a csgo workshop map to train your aim and reaction

Workshop has alot of AIM training maps and you can play surf