You will notice certain balls with power ups on them. Always keep an eye out for the multiplier balls and match them quickly, because your multiplier will go down if you don't keep it going. Remember that you can switch the ball you're shooting by pressing B, and if you need a certain color quickly, look for an open gap and just shoot balls off the screen until you get the color you want. Also, power ups like the triple shot, lightning bolt, and especially the laser will give you any power up you shoot without matching 3 of the same color. I love using the laser to pick out the multipliers, and then shooting a bomb power up, and using the bomb on more power ups... makes for a good combo!