One little-known tip that has helped me quite a bit when leveling up in Diablo 3 is checking NPC vendors for items. I am talking about the computer controlled merchants that sit in town and are marked with a loot bag on the mini-map. A lot of players check these once and then assume that these vendors have nothing good to offer.
However, the truth is that the stats on the vendor items are automatically reset each time you join a game. This means that you can join a Diablo 3 game, check the vendors to see what the items they are selling are like, and then leaving the game.
This is particularly useful for finding all sorts of equipment. For example, if you find a vendor that sells rings or amulets, you can keep joining and leaving games until you find a ring or amulet that has the â€œKeen Ring of Woundingâ€ stat. This increases your attack speed and weapon damage and a level-appropriate Ring and Amulet set with these stats can literally increases your damage by 25-100% (depending on level and weapon quality)!
Additionally, you can look for weapons with good attributes, such as Keen (weapon name) of the Eel/Snake/Winter/Flame, as these weapons tend to have the highest DPS out of any you will find. By applying this Diablo 3 strategy, you can essentially get a free look at blue items and then keep joining and leaving games until you find one with the stats you want.
If you want to take this Diablo 3 guide a step further, you can often buy a lot of these items and then re-sell them on the Auction House for a nice profit!