Play with your friends bro, even if your having a hard time. Play the vanguard role hang just a bit back watch their movement, listen for call outs, and ask what they would like you to do. As your awareness goes up, map knowledge and gun skill goes up you'll start contributing more and more. Playing in a fireteam is the best way to improve especially if they are better players. That moment you snipe a streamer or outgun the top player on the opposing team will make it all worth it even if it's your only kill.