Having just "beaten" the game (with a healthy buffer over the requisite score), and seeing as how the other threads in this forum are all locked ( =( ) I figured I'd make a thread with tips and see how others approached the game.

• Pay attention to what you're up against for sure, but don't be too discriminate about what you match. Particularly if there is a four- or five- in a row you can match, it's probably more worthwhile to do that match than to try to hunt for the tile type you want. This especially applies to wood, stone, items, and shields.
• Get the chests-are-one-key upgrade as soon as humanly possible.
• Save your items for dragons, then just dump them all on them.
• Buy all the armor upgrades first.
• You'll get tons of key-type items in the game. Cruelly many, even. Clear away keys with almost as much prejudice as you clear away wood and stone. Particularly once you obtain the key upgrade.
• Different enemies are susceptible to different types of damage, but you hardly even have enough choice to think that deeply about it. Just attack with whatever.
• Omnom as soon as you get a food item unless it'll push you past the reset line.

Interesting points:

• If you have two tiles of a type, then shift in a rainbow tile, then two tiles of a different type, all five will match.
• If you match five, you gain time.
• If you unlock a new rank, the objectives carry over to that rank. Don't bother holding back a rank just to clear away your remaining goals.

Nope. The new rank unlock itself is always a score objective that's clearly marked as a mission. The point is just that each additional rank comes with 5ish new objectives that are added to your current list, and the next-rank-unlock won't be on your list until you clear some of the other stuff that came with the current rank.

I think the single biggest piece of advice is to just always keep matching. Even when running in between encounters. The game hints at this with the "keep a clean board" messages. And anyways, I went from download to game complete in less than 3 hours. Taking your time isn't the worst thing in the world, because there is literally nothing to do once finished. The high score runs aren't really that fun, even with all the difficulty+ potions on.