Originally Posted by IvanLedah21

Well, EXP is useful for leveling to increase max stamina (especially important at lower levels where going to work/school/etc. means you end up wasting stamina regen because your max is too low. At high levels it's more or less just a free refill with a slight boost to max stamina (and every 10 levels past 100 gives a FL slot up to 150 I believe)

As for Life Crystals, Event Map ?-4 and ?-8 is almost always the best for those

Personal Preferences and different play styles - Just going with another advice of another person who said to new players of FKG: "Don't rush, just enjoy yourself"

I did that since Julyu 2016. I'm happy with being lvl 100 or so at this point. I didn't finish the July events, but I manage to finish all other events from August. This game doesn't have huge difficulty spike like Aigis. There is no need to grind for Exp and other stuff from the start.