I haven't read a chess book, but I did some tactics a few years back and got to 1300-1400 online. Around that rating, the most important thing is to learn how

I haven't read a chess book, but I did some tactics a few years back and got to 1300-1400 online. Around that rating, the most important thing is to learn how to not blunder. Doing tactics is the most helpful for that. You also learn to spot and take the most advantage from your opponent's blunders.