Notes

EXPAND at the cost of MI. You can expand to one province in a turn as any culture except nomads - nomads can expand to 3 provinces in a turn. If you are an Imperial or Absolute Monarchy or an Imperial Dictatorship, you can also expand more, +1 province per turn. Only land expansion is available at the beginning - if you don't count the many gulfs and straits that allow for expansion over them and islands counted as a part of another province.
UPGRADE TECHNOLOGY to unlock new troops and bonuses, if you have enough Influence Points - cost lists down below. Unfortunately, Nomads and Hunters can not upgrade technology.
HIRE troops, ships, missionaries and other - cost lists down below.
REACT TO EVENTS AND MAKE OTHER RP to create beneficial situations for you.
MAKE DIPLOMACY - create alliances, issue embargoes, declare or end wars, make royal marriages (only for nations with nobles), at the cost of 1 FI per action. Wars with no Casus Belli cost 8 MI. You can Force Unconditional Surrender for enemy morale/2 FI.
DO OTHER ACTIONS: Nomads have access to two special actions - Migration and Razing. Razing will cost at least 4 Influence Points of Foreign or State Influence, but per every 4 points lost you gain 1 MI. Migration means you give up a province for another free province, and gain a short boost of income in accordance. Hunter cultures can also migrate. Other special actions include upgrading units (1 turn and 2 MI to Veteran, 2 turns and 4 MI to Elite, 3 turns and 6MI to Royal; participation in battles also accumulates experience for your units) and changing main trade nodes. You can Loot a province to reduce its usefulness to enemies.