In the single player mode tactic you should be following is to make sure first that your biggest planet stays so well stocked that there is no chance of it being taken over. Then once it's essentially invincible, send your troops outward to take over planets from biggest to smallest.

Before you start with it keep in mind that once you get your Galcon ID multiplayer mode becomes the only mode available.

In multiplayer mode you need to be extremely fast so you don't get taken over right away.

Win enough times and you get to rank your flag up. The more experience you gain, the better your flag rank will be.

Don't spread outward too quickly in multiplayer mode or you are bound to get your big planet taken over quickly and that is the one that you want to protect the most.

Winning gets you Galcon coins witch are used to buy cosmetic enhancements, such as changing the look of planets or ships.

If you are on a team in team mode gang up on one opponent at a time. Using your combined firepower to take over enemy big planet is the goal.