Listed at the top of the Solo Action Card is the type of action and whether or not you may Follow it.
Also listed are the specifics and requirements for the action, and what constitutes a Failed Action.
Note: Abilities from the Heroes or from the Capital City may alter the normal rules of these actions.
The Solo Actions are:
Recruit
Build (Capital City Track or Towers and Vessels)
Research
Tax
Attack
See related rules.