Tips

Watch pro games, you'll learn many things in the placements.

Have nice com and know callouts.

Crosshair placement is crucial.

Perfect sensitivity/crosshair

Have fun

Practice on training maps to get better aim also customize your crosshair.

Literally, just train your game sense. Think about what you would do in your enemies shoes. If you can figure that out, you will be able to win most fights by setting up correctly.

Play 5000hours then buy the game again to smurf and rape people lower levels/skill level than you to boos your self-esteem.

Play 5000hours then buy the game again to smurf and rape people lower levels/skill level than you to boos your self-esteem.

Play 5000hours then buy the game again to smurf and rape people lower levels/skill level than you to boos your self-esteem.

Learn to hold angles. Don't peak further away from a corner because the enemy will be able to see you before you see them. When holding (let's say bombsite and you are in a 1v1), don't peak, let the enemy peak you. Keep your crosshair (and hopes) up. Don't stare at the ground. Have good headphones to hear enemy footsteps. Communicate with your team.

Keep playing, practice makes perfect. And fixing stuff such as sens and hardware should make it easy as well to learn.

Practice in Casuals and deathmatches. Learn the basic guns and find what you like.
After that, start learning your way around the maps and start learning callouts.
By that time, you should be more than capable of helping your team!