To become a professional lurker, you need to spend a lot of time in the game. You are the "ears and eyes" of the upcoming round. You need to find out the information about the opponent which you can use. And use this information against the enemy for the interests of your team. It is what the lurker knows about the opponents, how they play, and their rotation to other positions that allows you to exploit weaknesses on one of these flanks of the map.
The opponent can play aggressively, and the lurker will punish for such a mistake and will take advantage of the situation for which the opponent will pay. Although playing aggressively has many advantages, in some cases, it will be more correct to take a step back and play passively. It is very important to know when to play aggressively. This is about studying the map, and it is one of the few things that separates good lurkers from bad ones. But it will depend on your opponents and the map you are playing on.
When you play for the CT site, you can even ignore this role. Of course, at some points, it can directly work, and you can win a couple of three rounds thanks to this. You need to do this only with great confidence in your actions when the enemy does not expect exactly such actions from you.
It is best to use this role when you play for T-side. Study your enemies, and their movement around the map, and surprise them to do important kills. And you need to remember that you must be sure that you will not be killed on your first kill. Your task is to draw attention to yourself while the rest of the team performs the task of getting to the point with minimal losses.
Having information as a lurker means "fully reading the opponent's game, and passing this information to your teammates." The fact that you can predict exactly what your enemies will do gives you the right to play aggressively, but you have to be careful; it can be a special trap to determine your location on the map.
The enemy team feels very uncomfortable on the map when they know that the lurker may not be far away, which makes the enemy morally insecure and gives you an advantage over the enemy.
Since you act alone, all your teammates can offer is some information that will help you, then you will get new information. You can share it, and the team can use it for their further success in the round or even in the game. Communicate with your team as much as possible, offer your draw options, listen to others, etc.
If you haven't done so already, check out the games of popular professional players playing the role of a lurker. You can highlight the game of such players as b1t, ropz, Magisk - players know how to act in certain situations because not many pro's have such experience. You can also watch the demos of the Swedish legend GeT_RiGHt; his actions were learned by more than a dozen players from his experience as a lurker. Try to play CS more because the more you play, the more you learn about the game. Learn and develop your new goals in CS:GO.