The system is simple at heart: If you tie against a player with the same strength, you both stay at your strength. If you win a against a much stronger player, you win more points than if you win against a stronger player, which still gives you more points than if you win against a weaker player a.s.o. The same goes for loosing: you lose less points vs. a stronger player than vs. a weaker player.
To improve your rating, you simply need to win > 50% of your games against (at that time) same level players. Of course, likely 40% against slightly stronger players will also work, as 60% vs. slightly weaker.
The point is, if your rating is not consistently going up after let's say a bunch of 20 games against random players say at +-5 around your current strength, than you are most likly not that much stronger than your level indicates.
This is not a slight against you, but most not top ranked players think they are better than what their level indicates, that includes myself. They only want to play against better players because when they "inevitably win", they go up faster than if they "only win" vs. weaker players. If you are a good player and start, that will work, becasue you are better than the starting level. But at some point you reach a plateau, and that is likely what your current strenght really is.
So I wouldn't try to have a strategy to "game the system". Play against player that are around your current strength, and then you should rise if you are better then them.