Try to keep the corners as clear as possible. It is easier to get trapped in the corners. Keep them as clear in the event that a green tile gets trapped by red tiles and shrinks the playable level. This will also make it more unlikely for new green tiles with your required numbers to appear. If you can safely move in and out of a corner, getting those green tiles off the board will keep the board at its optimal size. When you eat a tile that turns tiles from red to green, they can be eaten immediately because they change colors as the snake is moving. Do this to avoid getting trapped. If you get stuck in a corner, if your snake is short enough it may be able to get out, or a low value tile you eat will shrink it enough to open an exit. In later portions when the tile values begin appearing into the millions, it will be unlikely that you can focus on which tile is the lowest in value. At this point, focus on corners and serpentine movements.