My name is Bruno, and I have 10K hours in Counter-Strike. I actually dislike the question "How to Improve At CS2", because it can mean so many things. A better question is "Where do I still suck?", because that immediately narrows down what needs to be worked on. Let us start from there.
Read this part, it is actually useful
Responsibility
You need to realize that you are responsible for the outcome of every round. It comes down to a lot more than just your aim or the extremely misused word "gamesense". You are a part of a unit in every match you play, and you must decide to fill the role that unit is most dependent on, every time you play.
"My way or the highway" just won't do it here. You might have a talent for playing the AWPer, but to become better, you cannot insist on always playing the AWP. What if you end up in a lobby, or a team, where someone else wants to play the AWP? Are you going to whine and cry until you've got it your way, or are you going to take this as an opportunity to work on something else, and becoming a more experienced player?
Start as a generalist, not a specialist
Even outside of esports, experts recommend young athletes to attend multiple different sports before they commit to one fulltime. It is not recommended to only play football from the age of four.
The same goes for Counter-Strike. Not only should you be open to try different games from time to time, but you should definitely not only play one role. You don't have the luxury to decide what role you're going to play. You need the experience first, and then you can start deciding where you want to put your main efforts, and trust me, that will take time.
Be like water
This is a known saying in special operations groups in the military. They don't say "if this happens, we do this", no. They drill multiple scenarios, over and over again, and they write down what went wrong or could be improved. But they do not make all their decisions beforehand because they know that all scenarios, are always different.
This is absolutely the same for Counter-Strike. Everytime you enter A site on Mirage, no matter how many thousands of times you've been there before, it is always different. You can have your routines, what utility you start throwing, where your first contact position is, but you must be open to take in the information coming your way to make the most tailored decisions you can.
It may appear as a good player just re-uses a bunch of different plays every round, but if you narrow it down, it is the small things that matter; the timings they peek on, the intentional footsteps or the intentional silence, the repositioning, the utility usage. It's all based on information they recieve. It's thousands of hours into training "adaptation", and not a giant playbook in their head that makes them decide upon "if they do x, I do y".
You are the reason you lose a game, every single time.
This may come of as harsh, but the good news are that you can do something about it.
You might say "My teammates were toxic, that's why we lost". No, you just couldn't deal with the fact that they were toxic. CS2 is a game played by millions every month, and you are so absurd that you don't think you'll ever come across toxic players? If you aren't capable of dealing with that, you shouldn't play Counter-Strike.
You might say "I had 25 frags, and my teammates had 5, what more can I do?". Ask yourself, why didn't you inform them about how they should play? You clearly figured out the opponent, so why don't you let them know how to do that too? Maybe, just maybe, you kind of enjoy that situation. It helps you think that the responsibility of the defeat was not because of you, and your childish mindset still enjoys being on the top of the scoreboard - but you don't fool me.
You might say "I tried to teach them but they didn't listen". Trust me, they listen, you just don't know how to communicate it properly. It is your responsibility to communicate to your team in a way that they are open to listen to. If you haven't put your efforts into learning that, then that defeat too, was because of you.
You might say "I did communicate my ideas well, but they muted me, called me bad words and were greifing". What did you do then? Did you take that game any less serious? Did you let the thought even just once enter your mind saying "We will lose anyways, I might just do this stupid play". The second you let that get into your head, you've lost.
This is the name of the game. You will come across toxic, bad, ignorant, and chaotic teammates. You can never do anything about that, but you can adapt to it in the best way possible. And for some reason, you still think "How to get better aim" is the main thing that's going to help you improve.
Keep track, always
A small thought-exercise, who do you think improves faster? The one at the gym who keeps tracks of their sets, reps, and weights, or the one who just picks their exercise based on mood and intention?
The same goes for Counter-Strike. When you lose a duel, what do you do? Do you pick up the phone and start scrolling? Do you start shittalking in chat? Do you let the anger or irritation consume you?
What you should do is this; take a breath, and examine the situation for yourself. Why did I lose that duel? Did I peek on a bad timing? Why was that a bad timing? Should I have used utility first? Did I miss my bullets? Why did I miss my bullets? Did I fire too early before my crosshair had fully landed on my opponent, or did I actually think I was going to lose the duel beforehand, was it a mindset thing?
If you examine yourself at every opportunity, you'll see progress faster than anyone who thinks a better gaming monitor is going to save them.
Consistency
I won't spend my time explaining why playing consistenly is good. It goes without saying. The only thing I'd want to add is that it is better to play on a consistent basis, rather than playing too much. I've had weeks where I've played 8 pugs a day, and weeks were I've played 3 pugs every other day, and it has come clear to me that sometimes, less is more - if less is consistent.
What now?
Rethink your attitude towards the game and examine your own flaws. Come back to read this article every now and then to remind yourself. Watch professional players, be curious to learn more about the game, utility, map knowledge, aim and mechanics.
I built SCL.GG where we offer prematch tools, such as training and practice servers, and postmatch tools such as 2D Demo Replay and Playbook. Use it if you wish, it is good stuff.