I did this with my Cannon Shooter not one week ago. I started around 7pm on a Thursday and with sleep dinner rest etc. etc., leveled to level 70 on Friday at 10pm.
This is how i did it.
Level 1-30: Complete ALL Cannon Shooter Quests until you kill King Clang
Level 30-36: Finish ALL Mushroom Kingdom Quests until you receive the medal
Level 36-50: Use Level-Up Potion, CD’s at Kerning Square and some Ludibrium PQ
Level 50-55: Drakes
Level 63-66: Zeta Grey
Level 66-70: Sand Rats
Item buffs used: The daily 1hour 1.5x coupons given by Maple Admin.
Level70-81: Use Level-Up Potion lol
And i stopped here because i only wanted the Link Skill from Cannon Shooters for my other characters.