To farm AH, there are a few things you need to remember to make it succesfull.
1: Autionhouse Addons are a must. You can see which AH-posts are cheaper then the rest.
2: AH will always take 5% of the selling price!
3: Know that someone is always undercutting you! Remember to check AH regulaly to se of you need to repost.
4: NEVER flood the AH. You will never sell it all if you flood the AH, and that will just be a wast of deposit gold.
If you are a crafter, and craft stuff from stuff you have bought on the AH, here is a small math piece to help you post the stuff for the right price:
(X+Y) < Z*0.95
X is the ammount of gold used on the mats for the item to be created.
Y is the AH deposit
Z is the selling price
0.95 is to make up for the 5% AH cut in the selling price
If you follow this math piece, the difference between (X+Y) and Z*0.95 is your profit.
Good Luck, and have fun
Any Leatherworkers reading this, pleae stay away from EU Kul Tiras horde side