Short one this week. Here are some tables of common actions in the game. Any character can also use an action to perform one of the move actions, though if they actually move a second time, they can only go half their normal distance.
The last blog post is all about this.
Use a Power
Activate a power that has the action tag in its description
Move half your move distance
You can use your entire action to defend yourself. Your defense score decreases by 2
Defend an Ally
You can use your entire action to defend an ally within one inch of you. If they are still within one inch when they are attacked, their defense score decreases by 2
Stand up from being prone. This takes half your movement.
You may use a consumable item instead of moving.
Interact with item
Interact with an item in your hand or in the environment (close a chest, open a door, blow a horn, etc)
Fall to the ground. Being prone gives you light cover against missile fire
Drop an item
Just let it fall. There it goes. No action required.
You can speak whenever you want. Your character does not have to wait until their turn to speak, so long as what they hope to accomplish by speaking does not require a die roll.
Draw an item
You may draw any item from your pouches without taking an action. However, using them does take an action.