How to break 800 elo?

Low amount of games, play more.

Hello! Generally, people at your level struggle with tactics, and having good fundamentals in general - watching videos/consuming learning material on general opening/middlegame principles, basic mates and tactics, easy endgames (and of course practicing) should definitely help. Try to write notes down, and read through them right before you play. Also you should regularly look at your own games, to determine your biggest weaknesses, and then focus your study time on those. And remember: Consistency is the key!

Hope this helped you a bit,

-Miss-Hurricane

Improving Your Chess - Resources for Beginners and Beyond.....

https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond

Over 5000 Award-winning Chess Tips - Dan Heisman...

https://www.chess.com/blog/danheisman/over-5000-award-winning-chess-tips

Dan Heisman Resources...

https://www.chess.com/blog/RussBell/dan-heisman-resources

Dan Heisman's book "Maximize Your Chess Potential" presents a detailed discussion of 164 of his most important tips. The book is outstanding. (I own many of his books - all are excellent).

https://www.amazon.com/MAXIMIZE-YOUR-CHESS-POTENTIAL-Heisman/dp/1836840063