how do I get from 500-800 in fast chess?
My advice would be to play some slow chess to give you time to think about strategy. Seriously. Once you have some practice having time to think about your positional strategy and tactics, you will be better able to spot these moves in faster chess.
If you are playing bullet though, sometimes the key is just to move pieces faster than your opponent so you don't run out of time. But I always think it is better to play to win than to win on time. Trust this helps.
Hi,
https://support.chess.com/article/437-how-do-i-get-better-at-chess
Maybe do some standard tactics or lessons to improve a little.