the two quickest and most effective ways to improve in chess is to study endgames and study the chess of grandmasters. i prefer bishops over knight in most cases. a pair of bishops is as strong as a pair of rooks, and stronger than bishop+knight, which is stronger than 2 knights. in correspondence chess games, i try to make the best move, but in OTB games, I just try to get the opponent to make mistakes. most players are very strong in tactics, but have never study the endgame, so i try to simplify to the endgame early to one that is in my favor. Rook and pawn endgames are especially important. Endgame study is really tough but the most rewarding as it can get you the most wins.