Make sure to keep any items with spells. You can use the spell/buff before a boss battle so it stacks. Just equip item like Spell: Shield, equip different item like Spell:Critical Hit. Repeat.
So if you use your pickaxe on the boss stage to get around the monsters, the next time he will create a row of monsters so you have no choice but to fight it. "Do you think you are so clever?"
For the "Plants Vs. Zombies" Badge you do not need to destroy every city, destroying cities in Santa's Land count toward your total in case you are having trouble with the other levels. (+) to keep alive!
For the Bonus Map:(War of Oil Badge) can easily be gotten by playing defensively and spamming air units to quickly take over the board. Make sure you over whelm the turrets all at once to take them out since they can regen. + if this helps!
A game that forces you to learn in order to get the hard badge. Curse your treachery of googling longitudes and latitudes, color codes, and other bits of random information!
Tip: You don't need your danger level(%) to be low, if your danger is 50%. It's a 50-50 chance you won't get attacked. Defiantly worth the risk if trying for hard mode or building your civilization faster.