Go to Bastok Mines. Near the left on your map is a circle. Go there and enter the passage, and you will be in Zehrun Mines.
Whenever you get Crystals in battle, put them in an auction for about 100 gil each. You will make good money this way, or you can put them in your bazaar for about 50 gil each.
At 6:00 in upper San 'Doria, the Wood Guild opens. There, you can by Arrowwood Lumber for 7 gil each. They sell for approximately 100 to 150 gil each. Also, the Luaun Lumber makes a profit, but not as much.
This trick requires three party members in Bastok. Behind the lighthouse in South Gustaberg is a bush labeled as "???". There, you can trade a Quus to have Bubbly Bernie spawn. He is not very difficult to defeat and drops a Steam Clock. If you set the second person to Quartermaster and make him wait at the entrance to Bastok Mines, he can run into the auction house and send it to the third person, waiting at the Mog House in Bastok Markets. The third person should take the clock to Malene in the very northern part of the town. She will give you 500 gil per clock. You can repeat this as many times as desired. Note: You can only hold one clock at a time, but you can have as many as you desired inside your delivery box.
Once you at about level 5 (depending on your main job), collect Silk Threads from Crawlers in either East or West Sartabaruta, outside of Windurst. They can sell at the Auction House for 1,000 to 2,000 gil each.
Go to the following locations in San d'Oria when at the indicated levels to level up easily.
Level 1 to 7: West and East Ronfaure
Level 7 to 13: Ghelsaba Outpost
Level 14 to 18: Valkrum Dunes
Level 19 to 25: Peninsula
Level 26 to 34: Jugner Forest
Level 35 to 43: Davoi (possibly)
Level 44 to 52: Xarbard
Level 53 to 60: Deep King Ramperre's Tomb
Level 61 to 75: Ifrit's Caltron
Synthesize a Goblin mask with a Wind Crystal to get a Sheep Leather.
To get Silk Thread very easily, defeat Crawlers in East Sartabaruta.
Synthesize a Yagudo Necklace with a Wind Crystal. This will get you three spools of Grass Thread. Synthesize them with Earth Crystal to get Grass Cloth.
This trick is useful to level up much needed spells such as Protect, Cure, and Shell. Go to a local residential area and stand directly outside your Mog House. Cast the desired spell on yourself until you run out of MP. You can also cast it on other players running in and out of their Mog House. Once you have run out of MP, run into your Mog House, replenish it, exit, and repeat. This saves a large amount of time from having to heal after casting. You can level up magic by casting the spell on yourself, despite if you already have the enhancement on yourself or have 100% HP. Keep casting and it will level up.