Getting items and gold is a big part of playing Diablo 3, so there is much merit in fully understanding the art of farming in this game. Farming is what separates the casual from the dedicated in this game, and you too can cross that threshold through following a few principles that shouldn't be too hard to go by. Here are the 5 basic tips to farming rare Diablo 3 items.
First of all, figure out what skills you need in order to get the best out of farming. Most of those skills involve splash or area of effect (AoE) damage. Combined with damage bonuses from equipment, you can kill tons of monsters all at once and get tons of XP, including XP bonuses from feats. Just make sure that you still have defensive skills that will let you survive adverse situations like being surrounded. If you have to get two or more skills of the same category, then you'll have to turn elective mode on from the game menu.
Best Equipment Possible
Perhaps this is the reason why you would be farming in the first place, but having that extra boost from the start with the best weapons and armor that you can get from the start is still enough to help. You can either just go for primary stat bonuses and some vitality and resistances, or you can look for magic find items to increase your chances in farming. You can have both, then wear the MF items whenever you encounter a treasure goblin, a chest, or about to land that last hit on a boss. It might just mean the difference between a good rare item and a blue or white item from a drop.
Good Farming Locations and Routes
There are certain areas in the game wherein you can get the most out of farming, which is why you should run through them repeatedly in order to get the most XP, gold, and items while you're not in Inferno yet. There are a few of these in each act, so you can still progress through the quests while farming.
This new feature that was added in the game is what made farming even more fun since you can ramp up both the difficulty and the reward. Monster Power is a pretty good idea in that you can take it higher whenever you are feeling that the game is starting to get too easy when you actually get better equipment or just playing a character class that doesn't get hurt as much.
Nephalem Valor Stacks
Finally, this is what makes farming really fun. When you get to max level and playing in Inferno, you can start getting Nephalem Valor, a buff that increases magic item drops, which is what you need to get the really good stuff. As long as you don't either die, leave the game or change your skills, you can stack up to five of them and run through the game while farming. If you think that you can take it, you can even ramp up Monster Power a bit, although you should make sure that you can handle it or you'll just waste the stacks.