Gathering is almost worthless for make money. Its main value is in saving money while crafting. Only HQ used to sell for a decent price. But even then prices drop so quickly it is almost not worth it. Its only getting worse with everyone saving for housing. Only small quantities for HQ items seem to sell anymore.

My advice for would be to take up mining and botany(keep them the same or close to the same level and they can share gear until they hit 50), level them with leves to 30(you can gathering everything for low level crafts and can gather elemental crystals, they general keep a constant prices, were bots will under cut you on everything else). Buy best gear. then start all the crafting classes. Hopefully your in a GC by then. You get daily supply/provision mission. they give you xp/seal. For the crafting ones you need to make 1 item(alchemy if its a consumable 3, but you generally make 3 at a time) For gathering you need to get 10 items.

Ok here how to make money doing these. Do all 8 crafts and 2 gathering ones everyday. Mostly, Gather only want you need to craft the items and what you need to turn in, though if its an ore, log, or alumen, might as well get 99 of them you will use a lot of them. Sell any HQ you gather(but not the ore,logs,moka grass,cotton or flax). while crafting try to go for as much quality as you can get before completing it, more xp and greater chance at HQ(which if is final product more xp/seals on turn-in), When crafting you going to make ingots,rings,rivets,plates,yarn,cloth,ex. that are needed to craft the turn-in item. If it HQs, sell it and make another for use. When you need shards, farm them from harvest point that give crystals. gather the crystals when you can and sell them. Those HQ ores and logs I told you to keep. Once you get your crafts to level 15(might want to use leves to speed up getting there)you will have a bunch of cross-class skills, that will make HQ items much easier. Use crafting to turn those HQ ore and logs into HQ ingots and HQ lumber, and sell those. Take the moka grass,cotton ,flax, turn it yarn. Now the yarn can be turned into cloth(depending you market can sell for more). Same with Ingots but they can generally turn into more stuff, pick whatever sell the most that day. Only sell then 5 at a time those. A big stack may take awhile to sell and the longer its on the market, the higher chance you will be undercut. Where 5 generally sells out quickly.