If you are selfish, and want to make useful things, go Herbalism/Alchemy or Mining/Engineering. These professions help the owners with consumables.
If you wanted money, go with gathering skills.
If you're nice and want to help your guild, ask what they don't have, and then become it.
If you need more advice or more information, please refer to the Trade Skill Sticky at the top of this forum :-D Best of luck!