How to improve Bullet ?

Pls don't encourage them

Play the same opening a bunch of times-- premove when you know it's safe to do so. Bullet is all about playing fast based on instinct (and some traps). Repetition and thorough experience of the opening (and some middle game) will make it easier to play fast and think less.

If you want to use this method of repeating an opening and getting familiar with it, I'd recommend using a universal opening-- an opening that works against any opening and can be played as white or black. This will give you the most opportunities to play with the opening.

try london system  it is safe to premove   

Thankyou ! I will definitely try it !

Always look the put the most pressure on your opponent

*to

Bullet tests the speed of your pattern recognition.

Make sure the common end games are second nature. Make sure you have your openings and replies as second nature. Never give up, keep playing as there is a high chance of a blunder from the other player. Don't play 1-0 if you have noticeable lag, play 2-1 or 1-1.

Mentally focus before the game starts, remember you are playing bullet (this sounds stupid but I often can forget I am playing 1-0 instead of 3-0 and slow my thinking go avoid blunders). Have a move planned before your opponent moves. If you need a moment to collect your thoughts, make a move like a check a couple times to gather your thoughts. If you only have a few seconds, and are winning with say, a rook and a queen, be very careful of stalemate, try to keep them in check as you walk them to an edge.