At each plateau (50, 60, 70) stop and grind through to the next level on GC hand ins, and on refined materials (turning logs into lumber, turning ores into ingots, etc.). Otherwise, focus on one of two things : Leves, or Crafting Log.

If you are doing Leves, do what you can to get HQ hand ins, and to conserve your Leve Allowances, only do the Leves that have you handing in three times.

If you are doing the Crafting Log, go by materials tiers. By this, I mean when you need a new ore, or a new lumber, or a new leather, or a new cloth type. Make everything once (Weaver will level a lot faster than the rest just due to the number of subcombines), or more times if you need to for your own use, retainer use, or for hand ins.

Leves are a LOT faster. But, they also tend to cost a lot more. Crafting log can actually generate a profit if you sell everything you make. Its up to you. About the only thing I’d worry about melding to your gear as you level up, especially since you can safely remove most of the Materia, would be CP. More CP is always a good thing.