[Misha_Bilous]

You actually shouldn't learn any strategies. They're usually too difficult and very often don't make any sense. There are two possible long-term plans: giving the checkmate and gaining more resources if you feel like you don't have enough to give the checkmate. In the majority of your middlegames (depending on your level) your plan should be attacking the king. Attack the king and align your moves with this plan. That's the only strategy you should have. Don't overcomplicate chess. Then you should play as much as possible and get feedback. Most of the time you get it when you make a mistake and your opponent punishes you. This way you can slowly, game by game, build the next layer of your chess understanding.