For someone who comes from "Ultima Online", professions are the holy grail of MMORPGs and they almost always disappoint me ... either due to various limitations or great shortcomings ...
They would always have to have a Voluntary character and be a "source of income", putting resources so that players who like it can sell their items safely and those who do not like them can buy said objects without sitting for hours in a town square or similar...
In other games there are sales systems based on a mixture of "auction" or fixed price in wep and a request / sale by mail within the game that work quite well ...
Going back to work ... there would be many things to assess ... make 2 large blocks (Collection / creation) and choose 1 of each ... leave it to free choice and put a limit of skills to go up ... it is a decision hard...
I am a MMORPG Player almost since the beginning of Ultima Online OSI (1997) and I have quite a bit of knowledge of their completely voluntary skill system ... and I offer my help and experiences to the staff if necessary.