Bullet (Exciting title, right?)
I know, I know, I am in no position to give any advice on bullet chess considering I'm only 2200, but I'd like to share my little bit of experience (the little I have) on the topic.
Inspired by Joseph Truelson's blog post on reaching 2200 bullet, I decided to give my own view on the topic of reaching 2200. Though he gave some sound advice on it, I don't think he mentioned some important points.
Bullet is horrible for your chess if you want to be actually good at chess (JT did indeed mention this, but I don't think he stressed it enough.) The whole concept of bullet is that it doesn't matter how well you play, it just matters if you can consolidate your position enough to be able to win of time or on the board in a time scramble (Okay, okay, I know, sometimes there are checkmates and sometimes one is actually winning on the board but that doesn't change that it doesn't matter if one plays good moves.) The worse part about bullet chess is that it teaches you to play on your intuition and not upon your "solving" of the position. With bullet, you can play a good opening and even a good middle game sometimes, but I've never seen a very well played endgame in bullet. This is because you simply can't play good moves when you've got hardly any time left on the clock! This is bad for one's chess because bullet teaches to not have to play well in an endgame - all you must do is time the opponent out! You can see how detrimental this is...
Another reason bullet is bad is because it's forgiving of mistakes. In rapid chess, your opponent, if good, will punish your mistakes. In bullet, they simply don't have enough time to rule out your sub-par moves!
Alright, now that you know that you should by no means play bullet, I will give some advice on getting better at bullet (Better as in +2000 [I know, that still isn't good. You can easily get to 2000 by simply just playing really fast.]) Regardless, there are still some techniques to playing fast and playing "sorta" good moves.
First, you need to play a system that you know well. You have to play an opening you know very well or else you'll get crushed on time and, sometimes, position. This is why most players play system openings like the London or 1.g3 2.Bg2 type stuff in order to get themselves in comfortable ground and be able to play the openings fast. Personally, I like to play 1.d4 2.Nf3 3.Bf4 because it gives me a flexible position that I know the plans in (It's important to know the plans in the openings you play because you need to be able to come up with them fast.) As black, I play 1... c6 2... d5 because this is easy to play and premove.
Second, you need a good mouse. There is no exception is this. If you have a slow, cheap mouse, you're not going to be able to react fast and not be able to move your cursor fast enough in order to move the pieces. Even if you do have a good mouse, you need to have the cursor speed on one of the highest settings so that you can move fast. It takes some practice to be able to control the cursor, but it comes with time. If you're using a touch pad or touch screen, I can't give any advice considering I've only used those options a little bit. I know many players do well with those, but I find touchpads being very hard to use. With touchscreen, however, I think it's possible to play fast and react fast. But I don't have any experience on this either. All I know about is using a mouse - and fast. This basically comes with practice, but there are some good techniques to playing fast.
Third, you must manage our time. You won't win bullet games if you spend 15 seconds looking for a winning move - unless it's checkmate. If you don't see the winning move right away, you probably won't see it - so, just play the first move that comes to your mind. In other words, use your intuition and don't worry about calculation (Maybe this is why I'm only 2200 - but it seems to work.)
A very important concept I'd like to point out is that you should not premove until under ten seconds (unless they're recaptures that are the best moves.) You don't really have to be up time. All you have to do is keep pace with your opponent for the first 30 seconds of the game. But then, you should start to play faster at the 30-second mark. Then, once the time gets very low at around 5-10 seconds, you should premove almost everything. However, you must make good premoves. Don't just hang all your pieces because, if your opponent is fast, ten seconds is plenty of time to take all your pieces and checkmate you.
Lastly, bullet is about making good decisions. There are many situations where you might be tempted to simplify into an endgame because you're up time or up pieces, but that doesn't mean it's always the best idea - like if your king isn't so safe or your pawn structure isn't very good. Another bad thing I see lots of players doing is that they don't try to go for an attack when they have the opportunity, they just try to consolidate their pawn up position and play passively. Never, ever, EVER, play passively in bullet! it's better to give up a few pawns for a rook on the 7th than to protect a pawn on b2 by playing Rb1. In bullet, most attacks work if you're not getting attacked badly yourself. Therefore, attack and attack! It usually works.
I hope by reading this you didn't become worse at bullet. I'm sure you already knew this stuff before reading my dumb blog, but I hoped you at least learned something.