If you’re stuck with a tile you just need to unload and it won't go anywhere else among your train or the public train late in the game, lay it on someone's train. But as a rule, stick to your own train for as long as possible to leave them "stuck". Given a choice to play a tile on multiple competitor's trains, always play on whoever has the most dominoes left. This way you don't risk someone getting unstuck from your tile and running out of tiles before you. You can be extra mean to competitors by laying a tile with the same caboose end you already know they can't cover. If their train is open on a |4, lay another tile that ends in |4. Just be prepared to hide under the table if playing with friends or family!