Well, if you've been doing your Job quests the only pieces you really need to worry about for the time being is your body piece, weapon, shield (if a class/Job that can use one, ala GLA/PLD), and accessories.

The first level 45 quest gives you your first four pieces of Artifact Armour for that Job (hands, feet, legs and head), which is arguably the best set you can get at that point in the game. You don't get the body piece til the final (level 50) Job quest though, so you'll have to substitute it for a while with something else.

It's a free set of 'blue' gear though, so it's technically better than anything crafted or sold at a normal npc shop. Plus you'll actually look like that traditional Job as well so if you're an old-school FF like I am that's worth it alone.