Put the motor on low speed and move quietly and slowly. Don't put it on high speed and give it a quick shot of power. The quick jolt of high-speed power can alert the fish to your presence and make them spooky. The Minn Kota Maxxum has impressed me with its quiet operation. Oftentimes, when the fish are spread over shallow flats, it works well to put the planer boards out.
Boards allow an angler to cover the water without spooking the fish.
Off Shore in-line boards are the choice of many. Don't let old notions about walleyes being a fish of deep water prevent you from taking advantage of the shallow action that walleyes can often provide.