On your way to Cape Caem, you’ll have to first take out the Niflheim stronghold at Fort Vaullerey and neutralize its commander. Stick to the shadows and warp strike behind cover and catwalks. It’s fairly easy to go unseen.
The not so easy part is the boss fight between Noctis and Aranea Highwind. Aranea has no weaknesses, so you’ll have to rely on skill to take her out. If you fail to block her attacks successfully, she’ll do massive damage that becomes hard to recover from. Imperial Soldiers will join her, but they’re mainly a distraction for her to wind up her ultimate attack. Face her in the air when you can as it will prevent her from pulling this move off.