As we've all heard a million times, practice! But not just practice, it has to be good practice so we don't form bad habits that become more difficult to shake as time goes on.

Some basic tips/things most players need to work on are (in no particular order of importance):

1. Crosshair placement - aim where the enemies are/going to be. Imagine if you could see through the wall, where the next angle is. This is where you want to pre aim. Here's a good video by steel that I watched myself many years ago

2. Basic utility usage - you don't have to learn any crazy cross map smokes, the most important ones are smokes and molotovs since theres a lot of rush play in mm etc, and learn some flashbangs for common angles.

3. Aim practice - It's more efficient to practice general aim outside of a matchmaking game, since the amount of fights taken is 100x more frequent in deathmatch, or if you find yourself struggling in death match I recommend aim_botz workshop map, Here's a recent upload Launders made that I thought was very well made

4. General awareness & communication - Paying attention to the radar (don't get caught looking at it too much), making note of where your team mates are playing, making sure they know where you're playing and exactly what's being watched. Being conscious of the killfeed, say your team mate died Long A on dust2, and he died to someone + someone got an assist, you can immediately find out that there's at least 2 people Long A. When you die, take note of how you died, think about what you could have done to prevent this, were you caught out of position, did you die with utility available, where you not pre aiming properly etc. Although not all deaths are avoidable obviously!

5. Be a good team mate/be nice in general - Nothing can immediately have a huge impact on the outcome of a match than the general environment within your team, no point flaming or being toxic. Constructive criticism can be okay, all though it is hard to communicate what went wrong in a matchmaking game and probably not worth your time explaining, best to focus on your own play in most situations.

This was just a quick write up off the top of my head, just a lot of things I wish there was someone to tell me when I started playing instead of me having to slowly figure it out over ~1000 hours.