depends on which one you play. overall, i beat most of it, and the best thing I can suggest to you is begin with the cannon as a starter and a grenade tower positioned in a triangle formation with the two cannons closer to the path than the cannon. Have enough space between them so that you can put a lightning tower between them, but only after you've had at least 2 of these setups. Note: You need a upgrade building after lvl 2 of an upgrade. You can have the mine building if you like, but overall you wont need it. Also, you don't really need the investment building until really late when you're mass building. However you can if you have extra cash.
