Put the highest tile in a corner. I prefer choosing the top left corner but it's irrelevent to the overall strategy.
Keep the row with the highest tile filled at all times.
Only move your highest corner tile when forced to, then immediately return it.
Now, there will be cases when the corner will be replaced with a small tile but that doesn't mean it's the end of the game. It will just make your position a little weaker and decrease your chances of getting a very high score. Nevertheless, getting a 2048 should not be a problem if you follow the above steps.