1. Focus on placing pieces horizontally not vertically

2. get used to watching the tetris online game  preview window and with practice you can plan ahead making your placements even more strategic

3. If you end up with an overhang it is possible to slide a piece under a line if you time it right.

4. for higher scores on tetris online game, aim at clearing more lines at the same time

5. as the game picks up pace you might have to abandon tip 4 and concentrate on clearing lines even if its one at a time.