Ok, this trick i used to get my mount at level 40, and yes you have to be level 40 (This is sort of begging but it can be eased on and ill tell you how you can do it). Anyway here is how you can make alot of gold fast:
Step one: go to Ironforge.
Step two: Find a level 60 or so.
Step three: greet him/her.
Step four: If he/she replies, Compliment him/her on his/her armor, weapon or mount.
Step five: If he/she replies "thank you" or something close to that, continue.
Step six: Ask if he/she is saving for his/her mount, if he/she already has a mount, compliment on it.
Step seven: (This step will decide if you get the money or not) If he/she replies, Say that you are also saving for your mount and you are, a small number of gold away from your mount ex. 1-10g and that you cant seem to save up the last bit. Then ask if he/she has that same number of gold.
(By using this guide you ease the beg on to them and make it seem like you really need that money.) He/she should give you the money if he/she feels you really need the money. (you built up trust by complimenting to him/her) Although it wont work 100% of the time, but it does work. I got 100g in 3 hrs doing this!
Hope it helps!