For crafting, you pretty much will have to level all to 50 if not up to just 15 for certain classes. Whichever class you want to start first is depends on which benefit you want first :
Carpenter has HQ finisher skill, HQ = more profit
Blacksmith has access to most other crafter tools so you can kickstart other classes with decent tools.
Armorer/Leatherworker/Weaver/Goldsmith lets you make gears that you can sell or spiritbond to make more materias.
Culinarian lets you cook stuff to sell, or prepare buff food for yourself and your future raids.
Alchemist not much but some of the mid tier materials like formulas and glues sells pretty high. Not sure in your server but I can make nice profit out of crafting stacks for those here.

For gathering, it's slightly more boring than crafting but you can earn steady money farming shards/crystal/clusters. Some crystals and raw materials can be sold for decent price but depends.

If you can level both disciples, you can start getting ehcatl sealants from the Ixali daily quests and sell them for a nice profit.
Hope this helps.