July 5, 2017
One of the best ways to level up for Gatherers is to visit the nearest Collectible appraiser and turn in items to them. It's very easy and will earn you some currency on the side. This method requires your gear to be pretty great, so if you're in bad/no gear, you'll have to try another method.
These are more time consuming the Collectables, but offer huge experience rewards for their completion and are viable at all levels. Just remember that you can only do a total of 100 before running out of tokens to do them with. 6 Tokens recharge per day (3 tokens every 12 hours).
Also consider simply purchasing the items you need for Leves from the Market Board - and always check the NPCs' prices first! Some players make a fortune by price gouging common Leve materials and items that can be easily purchased from NPCs on the cheap.
When all else fails, simply gather a ton of items! Every time you harvest an item you'll gain experience points. It's slow, but it's steady and it's cheap. Before heading out to harvest, check the market boards and see what's selling, and make it your goal to collect those items with the intention to sell so you can amass a small fortune from your effort.
Additionally, check if any of your Crafting classes require a lot of a specific material, or if a Leve that offers a lot of EXP needs one, so you can at least gather materials that are useful.
Grand Company Turn-Ins
Your Grand Company has a list of gathered items that they will want. This list refreshes daily and can be used to earn very high amounts of experience, usually about 10-20% of your total exp needed at that level! Turning in HQ items will yield even more EXP.
Collectables & Red Scrips (Graehl Gaming)