Under rating threshold (hideshow) here is the best strategy I have come up with... put down two basic towers and 1 elctro tower right off the bat... go ahead and level them up a few times...start your first wave and finish lvling them all the way up...add a few more basics and electros...finally add sniper towers when you have the money...sniper towers are ridiculous once they are fully lvled up...try and research +damage afterwards to help with later levels...(please vote up to help others)