If your goal is only to reach 70 as a dps class I would recommend arcanist 30-scholar 50-red mage 70. The job quest for scholar are both fun and easy and healing on a scholar could almost be done entirely by your fairy pet, making it even easier than any dps to reach 50 to become red mage.

However, if you want to set up your friend for success at 70 I'd recommend Dragoon or Black Mage all the way. These two jobs will be more complicated than red mage but not really by much and you spend 70 levels learning them so it might even be argued they are easier. Dragoon will be easiest to level through your msq, job quest, and hunting logs. Black Mage ......EXPLOSIONS!