If you are Iron - Silver, I suggest you listen to this.

1. Stop filling

I promise you that team comp does not matter in this elo at all. There are a lot of low elo players who play a wide variety of agents that they have little knowledge of. Stop doing this. You should ideally main 2 agents maximum that you like and are comfortable with.

2. Stop Playing too little or too many games a day

Many low elo players either play 2 games a day or 10+ games a day. Stop doing this. You ideally want you play 3 games minimum to 6 games maximum a day. Playing way too many games a day with make you susceptible to tilt queuing and you won't rank up significantly if you play too little games a day.

3. Improve your mechanics

I promise you that nothing else matters in low elo besides mechanics. The best way to improve your mechanics is to go in the range and try to hit bots on medium mode while counter strafing or play deathmatch and unbind your crouch button. Also if you are going to play deathmatch, use guns like the sheriff and guardian since they incentivize first shot accuracy and crosshair placement.

4. Have good coms

You don't even have to IGL. Telling your teammates where the enemies are, what utility they used and where, as well as how much damage you dealt to them will win you a lot more rounds than you think.

Anyways, These are the tips that got me out of low elo, if they worked for me they could work for you as well.