Early in the game, low-level troops are vulnerable to enemy Avatar harassment; make sure you watch over them and protect them whenever necessary
Make use of your double teams!
Don't play defensively. The game is about projecting power and taking control of territory. If you try to play defensively and stay in or by your base, you'll be at a resource disadvantage.
If you set the beacon on a building, your guys will attack the building until it's destroyed, ignoring any incoming attacks.
The right solo played at the right time can be devastating; don't forget you have those tools at your disposal!
