I really don't understand crafting.

[Highlanderx]

So, in general I should level crafting via making one of every item when I don't have any leves available?

No, you wait for more leves, then level it with those.

You should be doing them in Bulk, while using food and a xp bonus manual from your GC. Hopefully with an FC buff also.

While waiting go farm the ingredients you will need.

And you should never use leves for DoW/DoM, unless your hitting the cap and don't want to craft/gather. There are plenty of ways to level them. Not so with craft/gather classes.