It's hard to earn money in the game at the beginning, but with some help of my LS members, I found out the best way to make money in the 1-30 ranks.
Choose your starting city to be Limsa lominsa or Ul'dah.
To the south of Limsa Lominsa you can find alot of sheep and they drop sheepskin, they'll go for around 5k-7k each and you can easily get 30 of every 15-45minutes (depends on your luck).
You could also sell your windshards wich sells for 200gil (I would keep those though). Now you'll just have to Ul'dah and sell them for a solid 5.8k each and the next day it will be sold.
You can't really call this a guide, more a little hint to make a bit of starting cash.