I've been playing a lot of games on my alternate account (currently ranked Gold Nova 2) and I've noticed many players struggle to use the AWP.
There are a lot of certain aspects to the AWP that make it a great weapon but it also has some disadvantages that make it harder to use. Some of these include firerate, limited field of view, and inaccuracy while unscoped/walking.

Reaction time is one of the hardest things to master (or for some people, the easiest to master) when it comes to AWPing. One of the main reasons for this is because there aren't very many ways to practice reaction without research through community maps/workshops (many players don't check the workshop.) One thing I recommend is going onto the workshop and searching for the Csgo aim training map, which features a very big variety of ways to practice aim with any gun.
Reaction time is a very important thing when it comes to both styles of AWPing, which I will explain in a bit.

There are two different styles of AWPing, which are offensive and defensive (obviously in the title.) A defensive AWPer knows good positions on the map where they can hold an angle and depend on lining up the shots perfectly. A good example is SmithzZ of Titan, who often holds positions.
An offensive AWPer is restless, but has extreme reaction time and good aim, not afraid to shoot at point blank range. These depend mostly on "flickshots" and quickscopes, sometimes even using noscope technique. Again from Titan, a good example of this type of AWPer is KennyS.
I'd personally recommend that you learn how to AWP defensively, since offensive AWPing takes a lot more skill than knowledge to execute.

This is the part that most people struggle with, which is aiming. Sometimes I will watch a person AWP, and they take over 3 seconds to line up the shot, usually resulting in them dieing. There is a good way to fix this without even improving your gameplay. The first one is to lower your sensitivity. This will improve your accuracy in general for every gun, since your crosshair won't twitch off of the model while you're moving your mouse.
To improve your aim in-game, one thing I can suggest is not being afraid to move your crosshair into the target. When I say it takes three seconds to line up, it usually means they're moving the crosshair as slow as possible to the target. When I say "don't be afraid," I mean it's okay to move your mouse as fast as possible to flick straight into the target. If the crosshair is to the right of the target, flick your mouse to the left and predict when the crosshair will hit the terrorist and click at the exact moment.

Quickscoping and noscoping are ways to awp that are highly un-recommended for a beginner. The reason is mostly because there is no crosshair while you're unscoped, and also your gun is inaccurate unscoped. Quickscopes/noscopes are relatively inaccurate, so usually they're lucky if you're able to get a hit.