Clearing more tiles results in more points being awarded as well as increasing the amount filled on the fever gauge. You will not have total control of what color tiles you can use next. Each time another tile type is selected from your hand, the one you previously chose will switch to a different type. This will also happen if you take too much time to clear out a tile. One strategy to create large chains is to choose one type of tile to leave alone until you can amass a lot of the tiles together. When new tiles come down you may not always get what you need, and other tiles might drop into your working area, making it difficult to put the tiles you want together.