LTW attributes

If you were to prioritize when melding materia what would you always meld first? Craftsmaship, control or CP?

firstly look up what the stat caps are for each piece. Then meld in order of most expensive in cost of materia in your guaranteed slots to least expensive for your overmeld slots.

You really do not have much choice in how to meld, for most pieces. The Main Hand Tool, Off Hand Tool, and the Body piece are the three, I think, that you have some leeway on. The rest, you want to max meld as best you can, and that generally means melding specific materia to reach all three stat caps.

For the pieces that do not have attainable caps for all three stats I tend to go CP first, then I'll save the rest of teh room for whatever I happen to need later on. SE has a habit of releasing new recipes with higher stat requirements with some of their patches, and without knowing exactly what the Craft and Control requirements are going to be, I prefer to wait to see them, and to see if I even need to add more to my gear, before filling in those three slots.

What Roth said.

Meld the most expensive first.

Since I noticed that your LTW is only level 54 atm: I would advise you not to seriously meld anything until you reach max-level. Or at least not to spend to much gil on any melds, its not worth it for gear that you'll replace within two levels again.
Serious melding is only worth it on "endgame"-gear - and then its basically the usual rule of melding the most expensive stuff first.

(Also, if you dont mind me giving you a little advice: Crossclassskills are equally, if not more important to sucessfully craft. You dont only need certain stats, but also certain skills - crp to 50 for Byregots Blessing, weaver to 15 (or better 50), cul to 38, alchemist to 15 (or better 50). Currently for HW endgame-crafts you also want armorer to 50 and gsm to 54 - I dont know if this will change with SB or not, but it wont hurt to level those classes to get some key skills!)