I got my gatherers to 70 first, which made life much easier. While leveling, I first leveled all crafts to 15 for their base role skills Then I did Cul to 37 first for Steady Hand II and then Crp to 50 for Byregot's Blessing. Those two skills combined with Hasty Touch spam and Manipulation allowed for much more HQ items for leve turn ins, especially if you have HQ mats to start with. Then Wvr to 50 for Careful Synthesis. After that, it's more preference than anything. You'll eventually want all the skills as some say, even if you won't use them all. Use Ixali before 50, Mooglea from 50-60 and Namazu from 60-70, and use your leve quests for the job you want to focus on the most at that time. And don't forget daily GC turn ins.

I finally started seriously leveling crafts during 4.2 and just yesterday finished getting my last crafter to 70 and have them all fully geared in scrip gear. It is a grind, so be prepared, but the rewards are worth it, especially if you own a house.