Some variants you could consider...
Does it seem you are stuck? The moment you draw your Blockers tile can be very important. In this variant, you could search the Blockers tile before the game starts and put it next to your rack. Instead of taking a tile from your rack, you can also take your Blockers tile and place it on the board. This way it doesn't matter when you draw your tile.
A MORE CHALLENGING GAME WITH 3 PLAYERS
Before you start the game, put 20 tiles of a color that isn't used at random spaces on the game board. Deze tiles can be caught during the game like tiles from other players and also count as points at the end of the game.