In CS2, there is a built-in training mode where you can practice throwing grenades correctly. The only downside is that you need to know the correct throwing trajectory on the map yourself. For new players, this is not the best way to learn, but you can come up with some original custom smoke grenades, though that’s not the focus here.
The easiest way to quickly learn how to throw grenades correctly is through workshop maps. You just need to subscribe to one of the maps, and it will appear in your game. Then, you just need to launch it and try to remember what you will use in practice. Their purpose is to show you where to stand and how to throw with pixel-perfect accuracy. Below are links to current competitive mode maps. (You can see how to add such workshop maps to the game by following the link.)
Smokes on the map Ancient (Ancient Instant Smokes)
This map has really helped increase the win percentage for the CT side, as well as for the T side on Ancient. These grenades are available right from spawn, which is especially useful for taking control of mid. As is well known, whoever successfully wins mid is more likely to take the round, and subsequently the map.
Smokes on the map Mirage (Training Mirage Guide by ForceiD)
Smokes on the map Mirage are not just a way to diversify the game but a necessity, especially for the T side. You can’t push or fake without at least minimal knowledge of grenade throws.
Smokes on the map Inferno (Grenades and Prefire training Inferno by ForceiD)
The map Inferno, like Mirage, has many narrow spaces before the bomb sites, which is especially noticeable on B site. Without the default CT smoke, you won’t be able to win the round, or even enter the site and plant the bomb.
Smokes for the map Dust 2 (Training Dust 2 Guide by ForceiD)
Dust 2 can be called a map of rotations and fakes, and you should take advantage of this, especially when playing in a party. You don’t always need to shoot incredibly well when you can outsmart the opposing team.
Unfortunately, at the moment, there aren’t too many training maps available, so periodically check for new creations in the aforementioned workshop.