Take It Slow
Scan the entire board before every move
The biggest mistake beginners make is moving too fast. 2048 rewards patience, not speed. Before every single swipe, scan the full board: where will each tile end up? Which merges will become available? A single careless move can lock your highest tile out of position and cascade into a game over. Slow down — there is no timer.
Pro tip: If you can't see a clear reason to move in a direction, don't move that way.