Before you go ahead and purchase any shaft sukkeun. Know your average mid iron swing speed, transition time and guess at release early, medium or late. You can get all of these numbers with a Sports Sensors Swing Speed Radar with Tempo Timer. You might know someone with one. You can also video yourself with cell phone cam to get a better idea. There are few other ways to get it but I'd stay off of discount store simulators which in general are jacked up. Also look at true carry distance not roll out and be honest with yourself to get a better idea on flex, weight needed and trajectory. Because there are no golf industry standards for flex I have seen more who tried to self fit and wound up dissatisfied.
This is a good read. http://wishongolf.com/golf-shaft-fitting-selecting-the-shaft-so-you-dont-get-the-shaft/