This is a great question, and unfortunately, not one that I have a simple answer for. Each runner's "footprint" is different, and therefore, each runner has a different set of needs for performance shoes. That said, there are some tools that are very helpful. There are sites who will actually accept video of you running to help determine what type of shoes you need. Just determine whether you are a pronator, neutral, or a supinator (feet turn in, stay neutral, or turn out), and that will be a good starting point for shoe shopping. Also- if you are a woman, keep in mind that women's shoes are NOT just smaller men's shoes- women have different needs, mostly due to a wider hip, than men. Running is not a sport with a high cost involved- so don't skimp on shoes. The risk for injury with ill-fitting or inappropriate shoes is just not worth the 100 bucks! I just ordered a pair of NB, I'll let you know how they work out!