here's a begining tip to make gold. Run a level 90 character with at least 520 gear and has the profession for tailoring. Also make sure said character or any other character u might have on that realm is an Enchanter. Go to Pit Of Saron, set difficulty to 5 man heroic, kill the trash in the beginning (u can google the route) collect greens,frostweave cloth and possibly battered hilts. Once trash is dead,leave instance, reset, rinse and repeat 10 times or before the dungeon locks in one hour.
Your man goal is to collect the frostweave cloths. Now if you are not a tailor or dont have enchanting then u can sell them by the stacks (i usually get at least 500 total frostweaves per session which takes me 30 mins before im locked out). They go for about 30g a stak on my realm so that gives you 750g in 30 mins.
But the real money making comes if u have tailoring and enchanting. You take your frostweave stacks,create Bolt of Frostweave. Now that u have your stacks of Bolt Of Frostweave,you are gonna focus on all the GREEN BoE items u looted from the runs (which comes to about 20+)....Disenchant them and your gonna get stacks of Infinite Dust. then take the bolt of frostweave and Infinite Dust and create imbued bolt of frostweave.
Now that u have Imbued Bolt of Frostweave,go to your tailor supplies and buy Eternium Thread(you'll need 2 per bag) . You are gonna make Frostweave Bags with your tailor. They sell for about 150g+ each. I usually make about 12 of them per session which gives me a profit of 1,800g. If u are lucky enough,u might get a battered hilt which can sell for anywhere from 3k-10k (my server has it at 5k)
So u just made 1,800g in the 30 mins it took u to run Pit of Saron trash 10 times.
There,i started u off nicely. now go find some more ways to make gold