Skyrim: How do i make money fast?

Loot the whole of the Whiterun Jarl's quarters, there are billions of things just lying around, like Silver Bars, Diamond Necklaces, etc. Also, there are display cases dotted around, they contain some nice gear on occasion, like an Elven Sword, light but sells well.

the things dragons drop are worth tons of money. also search through chests and pots when your doing quests

doing quests and selling items

kill dragons sell the dragon bones and scales

you can also use inifinte gold cheat:

http://www.youtube.com/watch?v=SNVFw7Zym3Q