every 300 to 500 miles, and yes I track my mileage) I go in and get fitted for new shoes by someone who truly knows what they are doing.
First you take off your shoes and stand still, they look at your feet. Then they have you walk so they can see if your feet roll or pronate. Do you need a stability shoe? They factor in details like weight. Then they will come back with about 4 shoes of different makes and models for you to try. When I say try I mean it - run in these shoes get a feel for how they will preform daily. A good running shoe for me requires no break in time and feels 'right' the second I slip it on.
It is no secret where I recommend you go to get fitted (ala Runners World Tulsa) but there are many reputable running stores to check out. Please do not just run into Pennys or Academy and grab a shoe at random. Before I was fitted for running shoes I had awful back pain (this was the first 2 months of my couch to 5K experience) once I got new and proper fitting shoes that went away instantly and has not returned. Trust me - get good shoes, you will never regret it.
image taken from www.cartoonstock.com