How to improve at Chess960 ?

Not sure about the best answer to the questions above but I will give few tips :)

Learn the rules

Not only how does the knight move, but how castling is done in Chess960. Otherwize you may end up in a situation that happened to the FRC World Champion Wesley So during 2022 Knockout Championship (He became Champion in 2019)

After Qa8+ So performed castling, but Nepomniachtchi called an arbiter and she explained that it's not allowed, since one cannot castle under check. Wesley had to give up a knight therefore he resigned. Of course he would not have gone into this position (played 17...Qd8 instead of 17...Qe6 maybe) if he knew rules properly.

I can't say that rules are that hard but some people still find them confusing for some reason. All rules come from chess, you cannot castle

1. under check
2. If even one out of two pieces moved before during the game
3. If king jumps through attacked square during performing castling
   Tip: Don't castle too early. Sometimes it can be useful and cool to teleportate from one side of the board to the other (in case of an attack for example)

Practice

Well, you won't play chess960 better if you don't play chess960. The longer control the better, because you can't really think some setup/strategy through during blitz game, let alone bullet. I play mostly bullet Chess960 if at all, and it's no thinking, just some non-standard tactics which is also pretty fun, but not useful. GM Fabiano Caruana said that if one plays four rapid games every day for two years one can probably memorize all the starting positions.

Also if possible find and play OTB, either with evenly matched friend or tournament. Yeah, I don't think it's easy. There will be Chess960 open in German Kiel March 28-30. that's all I found :). Playing online is great too, you may join official Chess960 Lichess Team.

Understand and remember common patterns, setups, concepts

Garry Kasparov noted "In actual fact from the 960 positions 95% of them, frankly speaking, are poison to your eyes!"

But I guess there's some beauty/challenge in searching for harmony from any starting position. Some patterns, tactics, setups are specific to Chess960 and you won't see it in usual standard chess.
I'll give one simple example, but a lot of other ones come from experience and understanding of the game

1. Weak spots

We all know about weakness of f7/f2 squares in Chess but if white goes for the most primitive approach it takes at least 4 moves to get there (e4-Bc4-Qh5-Qf7). In Chess960 sometimes you can infiltrate as early as on move 2, so watch out for Bishops and Queens! You can watch the following old clip where GM Peter Svidler wins a pawn and a rook on move 2-3.
https://www.youtube.com/watch?v=9IwK0jle3dU
But with those pawns you should be careful, sometimes opposite side can get some compensation. Following example illustrates knight's danger, they can attack pawns and capture blocked pieces/checkmate early.

I can recommend these lichess studies with annotations to the games/positions
960 Brilliancies Project Part 1 and Part 2 by Tasshaq, GM RealDavidNavara, NM visualdennis, GM Former Player
analysis of four starting positions by visualdennis

4. Solve Chess960 tactics

As I wrote already, some tactics that do not arise in standard can easily happen in Chess960. Even examples above illustrate that. There are not a lot of puzzles right now but you can look at recent puzzles from Freestyle tour tournament

And other ones
2020 Biel Chess960 by Tasshaq
World Fischer Random Qualifiers Puzzles by Lichess
Offerspill FRC WCH Tactics by FM NaSil
Puzzle Pack: June '22 Titled Chess960 Arena
Original tactics in Chess960 by Tasshaq
Puzzles: Freestyle Chess G.O.A.T. Challenge by me
Puzzles: German Chess960 Championship by me
Puzzles: Chess960 Titled Arena July '2024 by me
Biel 2024 Chess960 Puzzles by me
Puzzles: Chess960 Shield 'August by me
Puzzles: Chess960 Shield 'September by me
Puzzles: The Champions Showdown Chess 9LX 2024 by me

Learn chess.

Yeah, surprising, but you still need to understand chess to be good at chess960. Endgames, strategy, common plans, calculation. I'll focus on that one :)

---

Thanks for the reading! Share your opinions and memes on forum. If you want to support me, hit like, i have a lichess team, and I am coaching (if you are interested contact me).