Here are some quick tips and tricks you should know before you set off on your adventure in Final Fantasy XV. These are regarding EXP.
How to get tons of EXP in Final Fantasy XV
To get a lot of EXP without farming, complete the quests from the tipster at the Chocobo village early on to unlock the burger dish. It gives a 50% EXP boost for only about 1KGils. Buy a new one as soon as you can when the effects are over. So you always play with 1.5x EXP boost. Then only sleep in the hotel in Alltissia to get a 3x boost for 30K gils. So basically, you get 4.5x EXP each time you bank your EXP. The money is not a problem as you get a lot by selling treasures. Never waste your EXP at camps, trailers or motels.
For AP, just try to kill with a warp-strike as much as you can to get 1AP for each kill. And you will encounter thousands of enemies during the game. So, do the math. Also, save all your EXP until you go to the next chapter. Then spend 10000 gil at the hotel in the seaside city that gives you 2x experience. More efficient.
Also, do all the Chocobo side quests and he will give you a meal that costs 1100 gil that gives you %50 extra experience. Always have this meal and bank your experience and you get tons of extra experience. Especially when turning missions in. If you can find a moogle charm as well which gives you 20% more EXP on whoever has it equipped. Also do the quest to fully upgrade the engine blade to the ultima blade. It is the strongest sword in the game.