It will depend on your expectations on what you catch. By September the thermocline will be fairly deep, probably in the 24 to 30 foot depth. If I were looking for large fish that is the depth I would seek. Off the tips of points is often suggested.
For eating size walleyes, I would troll a deep running bait like a Rapala Shad Rap over a reef or along the shoreline in 7 to 10 feet of water. If you start catching, keep coming back as there are probably more.
To get an idea of where the points, reefs, and the shoreline contours are, I would start with something like this one.
Navionics webapp. Use the roller on your mouse to zoom in.