you can play "sound" chess using general rules and get to about master level on lichess :
* trade a piece (bishop for knight and vice versa) when it's being less effective than the opponent's piece
* block opponents bishops
* block opponents pawns
* don't give opponent's knights a perch (supported by a pawn) on your side of the board, especially near the middle
* try to promote edge pawns to the middle or clear the path out of the way of your pawns
..there are many other rules, but you can apply these much more quickly (esp in speed chess) thinking "statistically" to improve your position. The end game is where it gets hard for humans and you actually have to think, especially if there are knights still jumping around, rooks and bishops are easier to visualize and block.