If youre serious about improving, then you will need to do the following:
1. Follow opening principles:
Fight for the center
Develop towards the center
Castle
2. Blunder check your moves: "Are my pieces safe?"
3. After your opponents move ask yourself: "What is my opponent trying to do?
You will need to do this on each and every move. If you lose on time asking these questions, then you need to play a slower time control. If you choose not to thats fine, but you wont improve.
A LOT of people here ask for help to improve. IMO very few of them actually mean it. Honestly I think they just want tips and tricks that will help while they continue to play speed chess.

Play at least 15+10 and on every turn take care of what pieces are attacked and if they are defended. If you lose on time it’s OK you just need to stop blundering. Only then will be sensible taking care of advanced concepts like blocked center etc.