Multiplier and other boosters can help earn extra points required for score challenges. Time boosters are useful for the coin collector challenges. When running out of time and your score is not that large, try to clear out as many tiles as possible, no matter how many there are. This will allow a wave of new tiles appear, increasing the chance of getting a booster tile.
Chains
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.
Gifts
You can occasionally collect a free gift, that may include coins and boosters. Each time a gift is collected, the time before the next gift appears increases.