Some general tips: If you don’t have any obvious combinations at the lower board, and are not setting things up for a diamond somewhere, try to do combinations as high as possible on the board, be it a color you need or a color you want to get rid off. This will maximize the possibility getting tiles you need, as it will produce the biggest change on the board.
When you are fighting a healer, especially in combination with field aid, it’s almost impossible that some healing will not occur if you dont have luck with your board. Try to set up a combination that will deal damage (not always possible, I know), charge your heroes and fire them together followed by the tile combo - and do this when the healer just fired, so they’re as low on mana as possible.
**taken from @Ornery
Please feel free to offer more advice or strategy.