How to be good?

You must play and play, skill comes overtime. Trust me, there are no secrest

Just use training maps, practice on your aiming and you'll get better in no time. Also try shooting at your target while strafing so its easier to dodge bullets and shoot at the same time.

you first should try some aim maps and try to kill every bot with 1 headshot only
then play alot of hours and you will see the def

Get some training maps from the workshop and just practice.

just look up an FPS config and stretch your arms before you play.

I found the easiest way to get better was to go on the CSGO steam workshop and download a map called: "Aim Botz" It not only allows you to practice your aim on standing targets, but you can also adjust both the speed and direction of the bots. You can also have the bots move at a random speed and direction.

Again, all you have to do is practice. If you have the time, why not refine your aim?