I'm not sure if this is really a New Player thing since I already have raid-ready gear, but it seems to be a good place to ask

I've been searching a lot for what materias to meld on my Dragoon, but I find no answers. Not only that, I want to level and play other classes, and I feel this may happen again in the future

So the question is: how do I choose the materia to meld for my class? I know BLM needs skill speed, but that means melding it in every slot possible? Should I put some int for more damage, or determination, or crit?

Thanks for the help