Hasty Touch, the level 15 Culinarian skill, is one of the most useful cross class skills you can get early in the game.

Just like with combat classes, you can cross class skills for crafting and gathering, so there are benefits to leveling mutiple crafts.

Once you get access to retainers you can store more items and get heavily into crafting. If you level them all and take your time, you can be almost 100% self-sufficient.