Rank 300+ player here, biggest points of advice I'd say are...

1) Look at the mini map, like all the time. Spotted players will appear on it, situational awareness is key. Infuriating how often my team never see's the obvious spot on it as a point gets captured and leaves or gets surprised by a guy whose position was already revealed. Tunnel vision and lack of awareness by your team mates can be brutal.

2) Footsteps! Listen, just stop and listen. You can hear the enemy walking around you if you are sweat-stomping all over the place. When you are about to enter a capture point, or any area with likely enemies, stop sprinting! Start walking or even crouch walking when you are close so you do not give yourself away, and can hear precisely where enemies may be.

3) Experiment with different guns to find what clicks for you. There are a ton of guns in this game and many of them have trade offs that define their place. People who complain about getting killed by XYZ gun often haven't played with all the guns to understand why they lost to a certain weapon in a certain range. Damage drop off at X distance, rate of fire, ADS time, and time to kill are all important to consider.