hey m8 .
its simple. open quest book and do first quests only , until reach training force core quest
(in each quest you can see which level is req for complite him , do only quests to lvl 10 , cuz i forgot which level is for Training Force Core quest
)
After this do only battle rank leveling quest from officer , other quests are waste of time
Even if you now level 100+ you can do first 10 quests
EDIT
If i remember names are :
lvl 10 - leveling First Combo
lvl 20 - Leveling first Aura
lvl 30 - leveling First battle mode
lvl 40 - Leveling Astral Board Skill
lvl 50 - leveling Second battle mode
...this is enought to go to Port Lux i guess