Any tips on how to get better at 4 player chess?
Try and not focus too much on one player as when I do this I usually find the other opponents setup a nice attack against me, so if you are annihilating one player, remember to watch out what the other players are doing.
I also try to not sacrifice my Bishops for knights or rooks as in 4 player chess Bishops are extremely powerful as they can attack both sides at the same time, whereas a rook needs to be vulnerable and out in the open to do this, and a Knight simply does not have the moving distance to effectively do this unless in the center of the board. I prefer to use the Knights for defending rather than attacking.
When mating an opponent be careful not to move just for the sake of a check as more times than not this allows another opponent to move in for the checkmate and ultimately they get the points for all your hard work.
Try and not exchange pieces unless it gives you a clear advantage, as the more pieces you and another opponent exchange you are giving the advantage to the other 2 players as they will be stronger with more pieces on the board.
Never give up and resign too early in 4 player chess. The game is ultimately about points and what can look like a bleak position for you can quickly change if a player starts focusing on someone else for example, allowing you to push a pawn for a queen and get back in the game.
I hope some of these tips helped.