How Can I Improve In Chess?

I'm 900 Elo how can I improve? What openings should I use and how should I play?

Any Suggestions 

I would recommend practicing puzzles and being creative and solid with your chess style and openings

What helped me was being consistant with one opening (any) so that you know it well. For me it was the scotch and the caro, but it's just preference. Also on lichess database you can see the most common moves in your opening and like this you can then look up the best response with stockfish and have an advantage (not everytime but often). Also when you make opening blunders, try to analyze them and understand why you did them so you don't make the blunder again. And of course puzzles

try London system, you will gain more elo than you could imagine.

The best tip that I could give to a player of below 1000 is that you should try the london as its the most solid opening you could see and as black you could play caro kann, its easy to play and learn. in the middlegame just try not to blunder and see what your opponent is threatning on the next move and neutralize the threat. In the endgame, walk your king , try to create a passed pawn and don't fall into any checkmate tricks. This is on my personal experience and this would help you reach atleast 1500.