Almost to DMG

Learn how to spray and learn the maps well. Learn where people hide.

Congrats on ranking up and I think 1 thing you need to learn if you aren't going to always be playing with premades is learning to adapt to the game. By this I mean take into account what your strong and weak points are along with the strong/weak points of the strangers you are playing with. See what your team needs and try to fulfill it to the best of your abilities. But don't force yourself to do something u absolutely suck at. For example Dust 2 counter terrorist, no one on your team is taking a sniper and peaking mid doors. You have no information about where the terrorists are going so what you should do is if you are decent at awping take an awp and go mid ... if you suck at sniping you can still go mid with an assault rifle trying to get information about people pushing mid or going cat

Considering that I don't encounter cheaters too often at LE, all you need to worry about is your aim. Lots of players around DMG+ have spot on aim. But make sure you know the map well, work on your aim, and find others to play with.

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Well I mean, Color might be bad and do 4/5 man queues but I'm over here solo queuing. Although I can't hit LEM :'-(
MGE to DMG is not that big of a difference in skill level so you won't be too surprised but you should expect people that know how to aim.
I rarely get queued against cheaters so should be fine. (As long as you carry like me)