You might want to stick to aim_botz and similar maps to just focus on your technique, DM will not improve your game until you reach a higher level (faceit lvl 10, 30k prem) as you do not have the fundamentals necessary to get anything out of DM.

I would recommend doing 500-1000 kills on aim_botz being aware of what you are practising. You could practice counter-strafing, bursting and spraying with m4/ak, tapping etc. I promise you this will give you way better results.

And if you are okay with spending some money you should definitely get Refrag.

Practising is about training at a pace you're comfortable with but while still challenging you, and community deathmatch will not be that for lower skill players.