You should do other missions first to level up your characters and have them learn some skills. Once you are ready for Thesis Hunt, go to Lutia Pass.
You will be up against an Archer, two Soldiers, two Thieves, and one White Mage.
The White Mage is going to be healing injured enemies, so you should focus attacks on that White Mage to make the battle shorter. There's a thief in this battle who has the Counter reaction ability. This means that if you attack him while standing next to him, he'll turn around and hit you. But he can't do this if you use a ranged attack like Black Magic. So it's best to attack that guy from a distance. The Archer, also, will slow things down because it can immobilize and disable your party. So, the Archer and the White Mage are first priorities for who to take down.
After Thesis Hunt, you learn about the clan wars. There are other clans out there who want to take over the different regions of St. Ivalice and control what goes on there. They will randomly appear on the world map as red soldiers. If you and a red soldier end up on the same world map symbol, you will automatically fight. These guys give you an easy opportunity to earn EXP and ability points. The pub guy in Cyril will mention the clan wars.