Remove whole columns (the in-game rocket is great for this) and get as many butterflies down onto your board as soon as you can.
The more butterflies you have, the more you can be filling at the same time.
If you get more than one of the same color you can fill them at the same time.
Once you get a butterfly, destroy a few blocks of it's color, then remove another column.
Another butterfly will fall, but if it's the same color it will need a few more blocks to fill than the first (so they will not both be released at the same time).
Work on filling them not only with large matches, but by blowing up the bombs constantly.
Destroying lots of blocks at once with the bombs will also build up the rocket faster.