1. Play as the Empire. Their forces are cheaper vis a vis their destructive capability.
2. Heavy artillery with ST/PT/AA escorts and a spotter (TIE or probot)is mandatory when laying siege to a base.
3. Get your air power up and running ASAP. They're murder on everything but the enemy AA units and they're quick.
4. Defend your base with light artillery, AA and AV turrets. The anti-infantry turrets aren't strictly necessary--helpful, yes, but not necessary.
5. Always remember that "The best defense is a good offense."
They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.