Best way to get Gil?

[Vurtney]

Roll a miner. Gather shards. Sell shards. It's not super fast but you can make 20k an hour with ongoing shard prices.

[Maero]

shards are big. I collect them from the enemies that drop them, either wind, earth, water or fire and then put them up on the market. I made 16,000 the other day just with the one sale
Metal from mining however i have not had luck yet but does save money for crafting