Ok heres my stratagy, put many storm troopers (50-100) in a dome like position. Next take 2, 4 legged walkers (AT-AT I think) and place them in the middle with 20 or 40 Anti-vehicle troopers and in the rear flank add 4, 2 legged walkers for support and to support the left and right flanks divide 20 units of your choosing (sorry, I don't know many Imperial vehicles and units). I suggest not using this stratagy untill you have a good and stable income to afford enough units to pull this off.