I am floating between 800-900. How to increase my rating



My suggestion is to limit games to 2 or 3 a day and stop if you are frustrated. Also watch agadmator(dont forget to suscribe)

Play Daily Chess and take your time before you make a move. Try your best to put in the knowledge you have in those games.

don't make blunders. (very simple ).
Agreed. Don't give up material for free. You don't win by making winning moves, you win by your opponent making bad moves. Look after your pieces and don't let them hang.

https://chessmood.com/blog/golden-method-to-increase-rating-in-chess Must-read article on this topic