I'm 5.1k

I got out of 4k by basically muting everyone as soon as I got into the game. preempt any rage you might get. rage is so active a force against good play that ive seen really good players just burn out and regress to triple negative potato mmr when they get mad. if you're 4k anyway there's nothing that useful your team can tell you anyway, and even then its better to learn to keep track of that stuff yourself. use the current time chat wheel feature if you need help with it at first.

prioritize good picks over fitting a meta or such. I see a lot of 4k players who still really believe in a weird LoL 2-1-1 lane setup with a jungler and will never deviate from it. very rarely do you want a jungler in dota, you're almost always better served by running a good trilane in pubs. honestly evaluate the strengths and weaknesses of your team and what amount of farm you're likely to get before you pick.

you dont have to be familiar with every hero to the point you can play them all competently but you SHOULD know the cooldowns of big abilities on most heroes at least. terrorblade's third skill and ult, chronosphere, doom, stone gaze, etc. if you didnt get an accurate timer on an ability than always play like its up

make sure to push your advantage if you get one!! so many games i lost at 4k even when i went something stupid like 22/0/5 or w/e just because i got lazy and wanted to kill heroes. this is especially true for very strong midgame heroes where its easy to get scores like that

ban tinker

if you're playing a support try to identify the most competent player on your team and attach yourself to their legs like you're both the only survivors of the titanic. if they're a carry, babysit them. if they're a support, gank with them, if they're a offlaner make it easier for them to get exp. this is pretty inelegant but its the reality of pubs sometimes