How do I improve from DMG?

As the title says. Im relativitly new to Csgo (started maybe max 3 months ago), Around 400-500h on it so far and enjoying the game but I wanna improve. I had this problem in double AK aswell that i rank up to dmg then down again within like 3 games. Been LE now 2 or 3 times and deranked all. I dont wanna derank :(

So how do I improve? I feel my spray is fine, maybe not the one taps tho but. Anything I should specificly do to improve?

Thanks in advance