There are so many types of political structures and government setups that it's hard to give a definitive answer. So instead, we recommend browsing the our picks or the MiroWiki's list.
Democracy: Politicians are elected and decisions are run by the citizens first.
Monarchy: One ruler makes all the decisions and the citizens abide. This can be similar to a dictatorship or authoritarian state, so many also incorperate voting as well as total power.
Parties: Especially in democracies, parties can help citizens choose who they want in power and what they want changed.
Forms: Think about how many people make up your government and what they can/can't do.