The bass drum produces the heavy part of your beat. To produce heavy sounds and play quickly, you must be relaxed. Take a look at my how to sit guide. When you place your feet on the pedal, never put your feet at the top of the pedal, near the chain. Place it in the middle part. It will make you be able to make you play with more power and quickness.

Sliding your feet up the pedal is a good way to do clean doubles. The first stroke is a normal stroke, and when the beater comes back toward you, do the second stroke, slide your foot up the pedal, and push down.

Pedals can be quite expensive, as some are 500 dollars. If you can't afford an expensive one, look on ebay for cheap pedals. Or, go into a local drum store and look at some pedals. A good pedal should have a good stirdy feel to it. DW5000 and DW9000 are some of the best pedals. Iron Cobra's are also very good. They cost a lot of money, so you will probably buy another pedal. Look for stirdiness and consistency.

Simple do single strokes with a metronome, and gradually go faster. If you have a double bass pedal, do rudiments on them.