The fastest way to rank up is buying Dragon Bones and Dragon Horns from Kollector in the Wu Shi Academy Island. Play the game normally and you should be able to just rank up fast on the way. The Konsumables do take a bit to reset so check every hour for the restock. Personally I'd reccomend assigning your stat points on attack to make things a lot more easier.

Whatever requires the Nether Stone, just leave it alone till you get to the last island. So it's going to be a while till you get the stone. You'll have to fight Scorpion and beat him, simple. I HIGHLY recommend getting the guard's mask every chance you have, it makes things so much easier and ignores those annoying ambushes. But if you need that XP, continue to grind those when they pop up.

If you have any questions go ahead and ask away, i'll try to answer to my best knowledge! Thanks for checking out my guide, please give it a favorite and award if you'd like! Thank you!!!