I found much more success once I learned to stop fighting bosses. You don't even need to fight them to move on or level up, all they do is make you lose equips, at least until you're fully geared and got all the skills you can set.
While this game is pretty good, the next iteration ought to be more tactical. I can have my transport copter carpet bomb the whole map plus enemy helicopters, my spy can bomb every ground enemy just out of detection range and can demolish entire buildings. The ammo cost is negligible, at least limit ammo for each unit, and make ammo capacity increase for each level up. Also money is too plentiful and one can grind for stars easily on old levels. Getting stars ought to be a one time thing for each level.
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