Clear out the 3 crypts in the Cemetery of the Forsaken, clear the large areas throughout act 1, then clear the 3 levels up to the butcher (as well as the jailer area in between levels 2 and 3 of the dungeons). It's fairly easy, even with a large amount of gold find and nerfed stats.
Start at the Heart of Sin quest in Act 3 on Hell difficulty. Teleport to Rakki's Crossing, run through until the end of the crossing, teleport to Core of Arreat, kill demons, kill Azmodan. On hell, he has a chance to drop level 63 and you will make about 400K+ an hour if you do it right.
Another good farming spec is the whirlwind barbarian. Farming act 3 with a WW barbarian is the main method of wealth farming of Kripparian.
If you are too lazy, you can buy Diablo 3 gold from RMAH, but you have to spend money. If you are willing to make money by yourself, flipping items on AH/RAMH is a good choice. However, you should be familiar with the economy of the AH. Just look for Diablo 3 items for sale with those stats: atk speed, Crit chance, crit damage, main stat, all resist and vit. You should learn some skills about make D3 items. I spend 15min to flip items on the RMAH. So far, I have been succeeded flipping windup wands (atk speed, ap per crit, crit damage, and/or socket) and rings and amulets. What I have to say is that it is really boring. According to my experience, the rate you can achieve is between 1 to 10eur per hour with this technique.
Farm inferno in Act 3 is usually the most popular method to make Diablo III gold.
You need to get good gear to be able to complete Act3 efficiently. Then I suggest you buy Diablo 3 items from online sites which are quite cheap. I usually use a windup wizard for that as it is by far the most efficient farming build for a given gear price, I think. You can jump from elite to elite by refreshing your wormhole cooldown on white mobs.
Depending on you build, magic find and luck, and generally speaking it is okay to earn 1M and 10M per hour with this technique. But you are more often close to 1M which makes it inferior to AH item flipping in my opinion.