find a cave, run inside, kill any and everything you can, loot everything you can that is worth 20 or more, load up everything you can until you cant carry any more, leave, sell everything, if you have ingredients make a potion and sell it, have any Ore or igiots *sp* make an item and sell it but jewelry is worth more and even more with a gem inside it.
making and selling potions is your best bet because some can be worth 500 +
Halted Stream Camp, kill bandits, mine all ore you can find, get Transmutation spell, turn iron to gold, craft jewelry and sell. Chop wood and sell to the innkeeper. Make a delivery from Farengar to Arcadia, which make you her friend - take all her free ingredients plus collect your own in the surroundings on Whiterun (hint: Giant's Toe + Wheat), make potions, sell. Make a run around the bandit hideouts around Whiterun, loot and sell as suggested above.
If you feel like travelling a little, go to Markarth. Deliver a potion from the alchemist to the steward, he pays good for that, plus it will get you more free ingredients from the alchemist. Get quest to kill the Forsworn in Kollskeggr Mine outside town, mine all gold you can find there, craft jewelry, sell.
And so on. Money is really only a problem at the very beginning of this game, at least as long as you don't spend it on enchanted jewelry and weapons and spell tomes, because those things are expensive.