It's probably all over the wiki but just a few things I've learned from n00b playing it while I poop:
-Don't bother fusing normal units you capture during quest runs. It turns out the cost to fuse is based on the unit level(the one you are gaining xp on) and not the unit you are fusing. So fusing a metal ghost thing is the same cost as a goblin at any given level....at least I think. I completely maxxed one of my units this way and wasted a ton of money. The benefit of fusing with the metal units is that your xp/zel ratio is way better so you don't go broke as fast. Fusing normal shit units I captured did have one benefit though, it maxed out the BB level for that unit!
-When you evolve it seems that the BB level of the unit gets cut in half.
-Keep the evolve units you find(idols/nmpyhs/mimics) or you'll be annoyed when you have to wait to the gardens day or farm some shitty dungeon over and over to refind them when you want to evolve. I usually keep up to 3 of each as a general rule of thumb. Just sell all normal units you find. Maybe start fusing them to your dream team characters if the "type" of the unit is the same(berserk/oracle/etc) because that could increase the BB level. I'd wait until that unit is at the max evolve level though.
-The only reason to do the arena is to earn the daily points for 4 wins. After that save your sanity.
-Use the wiki to read up on quests before hand. Nothing sucks like losing 20 energy or wasting a gem because the end boss rapes your face. I found that out with no $ spent and a bit of ignorance before I got to the wiki that the quests got really hard really quickly. Now that I have read up on a bit it's back to being somewhat easy. Basically don't just fuse/evolve/squad willy nilly. You can waste a lot of resources and then it's hard to dig yourself out a hole unless you pool energy for the special vortex dungeons
-Do the special vortex dungeons lol
In general they give way better rewards on all fronts of the normal quest shit. Plus you can plow the quests after when you get 1-2 badass units that you leveled/evolved.