Try to avoid using Fast Travel as much as you can early in the game and instead grind your way to the top as there is no alternative way to complete some of the mid-game missions.
Fully Restore Health Instantly Outside of Battle
To exploit this bug, just access the Active Members sub-menu of the Party menu, and select "Confirm Changes". Your party's full HP will be immediately restored. This is useful for exploring during damaging weather conditions, or if you want to very slowly cheat your way through lava.
Ocean
Do not forget the ocean when exploring as there are certain items there that need to be acquired to complete missions. An example of this is the Stardust Rod which is needed to complete 'Professor B's Return' mission can only be acquired in Syvallum waters late at night.
Professor B
Professor B, located in the Industrial District, is a likely reference to Doc Brown from the "Back to the Future" movies. He claims to be from the future. When you complete the mission he offers, you'll unlock Factory 1.21 AM, which is a nod toward the 1.21 Gigawatts of energy required to power Doc Brown's contraption in the films.
Skell Frames
After completing Chapter six, you can finally get your first Skell. A level 20 Urban Skell (the only level 20 Skell in the game) is given to you free of charge, and level 30 Skells can be purchased from the Weapons Terminal in Armory Alley in the Administrative District. However, additional Skells can be purchased with credits, or crafted with materials and Miranium. This is a list explaining how to unlock the rest of them.
Skell Frame
How to unlock
Level 50 Skells
Level up Sakuraba Industries to level 5.
Level 60 Skells
Clear the main story.
US0232 Police (level 30)
Complete H.B.'s final affinity mission, "Climbing the Ladder".
US0830 Dozer (level 30)
Complete Bozé's final affinity mission, "Bozé's Ignorance".
US0860 Excavator (level 60)
Complete Alexa's final affinity mission, "Rapid Misfire".
Fast Travel...