Have you been taking advantage of those clan trials?
If you haven't, you should be.
If you aren't sure, you should learn about it.
Quick tips,
First set of trials, you gain new bonus for every odd level.
For example, Negotiation I, choose level 1, 3, 5. The second and forth one doesn't give you new bonus.
It is similar for the other ones, but I have yet to test it.
The second set to trials, Negotiation II, each level should give you a new bonus but does not necessarily give the same kind, ie. going from Power 3 to Power 4.
When you get the dual type, ie. Negotiation-Adapt. Try to clear them, too. One of them gives you more AP, I think max of AP 3. I don't remember which one is which though :)
Negotiation I level 5 is probably the hardest one to clear, those annoying bunnies charming you and wasting your turns.
Here's some tips to clear them early on, highly recommend clearing them first thing when your chars are still level 4 - 6.
Their level seems to correspond your level, so, it's actually easier to beat them when they are lower level.
You should have at least 1 black mage master the fire/ice/thunder. Set the black magic to secondary skill so you can switch the rod to another char for another set of black magic. You're going to need the Fire spell.
Put equips on that gives you highest possible resist for those black magic chars.
So, you should have 2 black mages, more probably make things easier.
The law for this trial is that you cannot use range attack.
As long as you hit stuff next to you, you can even use a bow, it still counts as close range.
Knockback is counted as long range, which you probably already learned the hard way :)
Use your black mages and run up next to the bunnies, preferably 2 or more. You'll most likely get between 2 of them at most as they spread out. Then cast Fire on yourself. You'll hit yourself but with resist, it should be doing single digit damage to you while doing over 30 dmg to the bunnies since they are weak against it.
Even if you don't have high resist, kamikaze them still will net you a win.
Try to kill them off instead of weakening them. If you can pick to kill 1 or damage 2, choose killing off 1. Unless both your chars take turn before them bunnies.