Getting through the boards can be tricky sometimes, due to locked exits and Diggy blocks. Normally, it would need about seven moves per board, but one board is always rotten and needs twice as much which ruins the whole level.
The strategy's the same for all the boards (except the Treasure Room) - break your way to the exit, hit those Diggy blocks whenever you can, and make sure you also match combos of the color required to open the exit.
Advice: Don't use the Line Blast on the second, but on the third board (if necessary). It can help in Treasure Room, too.
As for the Treasure Room, standardly - match combos with highest number of "big" gemstones, and if you have Line Blast meter full, make use of it, too.