Punkgamer, after about wave 45 i seriously recommend you move your jeep to the back of the line and bunker down. Random crap will start costing you men.
When your first starting out try this.
1.advance with riflemen give the lowest rifles shotguns.
2. buy flame troop ASAP
3. at the top of a clear board, put your 4 grunts in top left and your flamer in top right.
4. save up to 20 points, taunting and shotgun/flaming enemys. Buy tank. Move your best rifles to bottom of screen. flamer to middle.
5. keep tank at top. watch it level up.
When one of your grunts dies, replace him with engineer mine the center of the map. move flamer up a little.
If flamer dies. buy office to concentrate fire. Ranger train and bunker your bottom troops.
This strat should get you 100+ waves from the beginning. But you need to move tank towards bazookas tanks for overshot. good luck.