I'm guessing others know this.. but thought I would take a few mins while my save loads to post:
6) Defeat gobs at gate to druid grove Level three!
I always skip this and go straight for the Dank Crypt first and then with LVL 3 I go into the Gobbo battle in front of the Druid Grove.
If you're really through on the Nautiloid, you can actually hit level 3 when you land on the beach ^.^
You used to be able to get extra XP by shoving/throwing the already dead bodies off the ship - they'd die again and give you xp - but that's been patched as of patch 7 - this used to let you get to level 3 while on the ship.
Interesting, I'll try that out. If that still works, I'll just tell myself that I'll use it to slay one or the other lesser devil or demon on the ground by throwing corpses at them. So the exploit is legitimate for me. xD
Fun Fact: If you heal the Enthralled Baker & Enthralled Farmer
There's an Enthralled Student a little further up, but nothing happens when you heal him.