Try trick your oponent- if you've got enough ground between you and them, attempt to climb some vines. I know what you're thinking- that's a sure fire way to get yourself killed. BUT- as soon as they start climbing, drop off the vines and grab on just below them. This will disorientate your opponent and give you the opportunity to get a few extra hits in from beneath while they're confused! This next tip is Breeze Island specific, but it should come in handy since it's played so often. In a fight near the cornucopia, try get to the middle canopy. Then, when you're opponent is coming up on to the platform, run out the opposite direction, and pull out your trusty fishing rod. Hit them backwards a few blocks when you're both in the water. Then, hop on to the shore and wait until they're about 3 block away. At this point you want to jump over their head, and turn around mid air. You can get a few extra hits from behind this way, easy!
So basically my strategy is to trick your opponents out of their powerful position, by getting behind them in any way possible! Always look for an opportunity to get behind their backs, you can always get extra hits.