Unlike previous Final Fantasy games Gill is highly sought after so you need to make sure you regularly find items that can be sold to vendors for some income. It is important that you do this often so you are able to position yourself financially to buy the best equipment.
Crafting Materials and Treasure:
There is crafting materials and high value treasure scattered all across the world so make sure you keep an eye out for it. Don't be afraid to investigate if something looks out of place, more often than not you will be rewarded for your curiosity.
If you find yourself struggling to progress in the game you can always go to 'Options' and switch to the Easy difficulty setting where you get resurrected when you die. This setting is recommended for players who are primarily playing for the story.
After battles look to rest at hotels that do not replenish EXP as these places multiply EXP twice, as compared to motels (1.5x).
This ability is available for 6 AP in Ignis' tree and will enable you to instantly scan enemies and learn about them. The information will also include their weaknesses which you can then exploit to the full.
Consider playing an assassin if the combat situation requires stealth, an assassin is able to sneak up to Human enemies undetected and eliminate their target in a single attack (Triangle button).
When selecting your combat stlye you may want to consider going to the 'Options' menu and enabling 'Wait' mode. This setting will slow down combat and allow inputs when the game pauses making the game feel more strategic.
As you only have a limited amount of stamina you will not be able to run around the world as much as you want. You can however save stamina and move more quickly through the world if you don't have access to a Chocobo by jumping during a sprint so you carry your momentum with you and regenerate some stamina mid-flight. This means however spam jumping often.
It is always worthwhile cooking food and eating it whenever possible as it will make your character more powerful which will help you in combat. You can always check to see whether or not food benefits are still in effect on by looking at your user interface.
You can become resilient to many attacks by phasing, this is done by holding the dodge button (Square). Although phasing will mean you won't have to employ dodge timing to actively mitigate damage it does mean your MP will drain if you use it.
When the night falls you will face enemies that are more dangerous. Although the enemies will be a higher level and harder to defeat you will gain better rewards.
MP is the measure of how many spells a character can cast. Every time a character casts a spell it will be depleted. When your MP is low you can begin regenerating it by hiding behind cover and holding the dodge button (Square).
Healing Magic Spells:
You may want to consider having Ignis in your party as doing so will give you access to several useful healing magic spells that will increase your party's sustainability considerably.
Use the warp attack on dangerous enemies that hit hard by delivering a powerful strike when they least expect it. The damage that you inflict will depend on how far you warped from so a good tactic is to weave in and out of melee range dashing with warp attacks to wear down an enemy.
Learn to take full advantage of magic spells like Fire by using them when it's environmental effects can be used to combo enemies.
If you need more Gill you may want to consider doing a Hunt quest. These side quests are picked up at diners around the world and involve killing a particular enemy. Hunt quests are worthwhile doing as they reward you a decent amount of Gill upon completion.