Combos definitely, go for triples as much as you can and watch the banana meter so as to avoid ending with a single.
Don't be afraid to go a little slowly, especially when dropping crates near each other or near the edge because you don't want to become stuck.
Ants are annoying 90% of the time, turn them to the nearest side to get rid of them.
Use earthquakes to move crates closer together where you can, it's much easier.
Remember, it is perfectly possible to combo crates on opposite sites by laying pieces above other pieces to be cleared. If that doesn't make sense, and I doubt it does, I'll post screenies to show what I mean if someone wants them.