[dreamer7]

I did something similar over the past four months, going from 1100s to 1680s on lichess.

At this level, you just have to find one tactic your opponent doesn't spot and you'll win the game if you have decent endgame skills.

I never spent much time learning openings but many people at this stage do. They'll learn certain traps to spring in the opening. But with careful play and some practice you'll be able to remember enough good openings to get into the middle game without much of a disadvantage.

Learning common mating patterns is very useful. In several games, I have been able to win with significant material loss because I could set up a mating net my opponent didn't foresee.

Lastly, it may help to know certain basic principles - control the centre, secure your king, don't isolate your pawns etc. But if you are an absolute beginner, it can be premature and you may start following these principles rigidly which will be detrimental to your game.