Items are very important in the early game so stock up on Potions, Elixirs and more.

Use Elixirs to replenish your maximum HP after dropping into a Danger state.

Take cover behind objects to replenish HP and MP.

If you Warp (Triangle or Y) to a higher vantage point you will replenish your MP.

Use the Wait combat mode and press and hold R1 or RB to determine a target's strengths and weaknesses.

Don't forget to check the Ascension menu when you have AP in order to learn new skills for Noctis and his friends.

To use magic spells you need to craft them in the Elemancy menu.

If you're doing a lot of running, turn on the Stamina bar in the Options menu.

Stop by every diner and talk to the person behind the counter to add new locations to you map.

Talk to the diner manager to accept hunting quests for XP and gil.