I'm on mobile atm, so I can't write a lot. But my recommendation would be to join a Free Company.

Don't worry about levelling multiple classes if that stresses you. If you mean the crafting classes, the in-battle repairs are the only relevant benefit to a new player, really. Level them on the side if you want to, but you're not losing out if you don't. I'm still only 20-30 in my crafting classes