First, know the habits and habitat that the fish you are targeting wants!
Second, Regular Sonar picks up fish best. Down and side pick up lake contour best. When out looking for fish, first I use the map to locate slopes, humps, and such that I intend to fish. Then I drive the area looking with Regular Sonar to see if the fish are there and then drop a buoy (in my case, I have spotlock on the trolling motor) and fish it. If the fish vanish, are appear thin, I can use down and sidescan to see what structure is there and maybe the fish are staging elsewhere and the spot I first marked was a travel point or they are chasing bait up and down a slope and therefore I just need to fish a larger area of the structure they are holding at.
I don't troll baits, the effectiveness is not efficient. I do have a downrigger and will use it at various times to suspend a bait at a certain depth, but just driving around with a bait dragging off a rod - nope!
You need to have your sonar dialed in really well and you can pull up on a school test fish a few seconds and if no bite move a little and if no bite, move on.
It is easy to find fish, but not easy to get them to bite. Some just won't open their mouth. Never sit for hours on fish just hoping it turns on.
Capt. Craig Copeland
2013 Nautic Star 2110 Shallow Bay Boat
Nautic Star Boats Pro Staff (nauticstarboats.com)
Redneck Fish'n Jigs Pro Staff (redneckfishn.com)