Fighting Units: Guild Expedition is a guaranteed source of unattached units. You can get an Emissary from the Viking settlement who provides 1 unit daily. Guild Battleground is another OK source as is the minor prizes in some of the Events that are a feature of the FoE annual calendar. For attached (healing/renewable fighters) military buildings are all on the tech tree as you progress through the research and ages.
Buildings: Tech tree and events, collecting blue prints when you Mo/Po other players and joining a Guild willing to help you to establish Great Buildingsare my top tips..