This will give you more opportunities to merge them with other tiles, and will make it harder for new tiles to block them in.
This will give you a large tile to build off of, and will make it harder for new tiles to block your large tile.
Even if you can't merge them into a large tile, lower numbered tiles can be useful in filling gaps on the board.
Each move you make should be purposeful and move you closer to your goal. Take your time and think through your moves before you make them.
Don't just slide tiles aimlessly, think ahead, if a certain move will block the board or it is better to wait for a better combination.
Even if you don't reach the tile of 2048, keep playing, with practice, you will improve your game play and increase your chances of reaching the highest score possible.