Rick, I'm in total agreement with Blue Cat Bob and Catfish Tim. Below is a screenshot from Grapevine. This time of year I start looking for places where a drift will take me across numerous different types of structure. I'll start in a creek channel and let my drift take me along the length of it where I'll cross out of the channel and over some humps and onto a shallower flat. I mean, like Tim said, don't waste your time if you're not marking fish. This time of year I start looking for fish in the first section of deeper water from where the feeding river dumps into the lake. Most of the local lakes will have a large area of really shallow water that covers quite a distance and then starts dropping off into deeper water. I'll start scanning where the water is around 10 to 15 feet deep. I may scan for an hour before I decide to drop down on them. I think sidescan is critically important for finding these fish.
Another thing, you can experiment with your drift speed. If there's a very light wind (which I can't believe I'm even saying after the spring we've had), I'll start off without the trolling motor. If I've got fish marked but they won't bite, I'll use the trolling motor to drift faster. Sometimes when the water is warmer, they'll be more active and I'll start getting bit with a faster drift, say .7 or .9 mph. So far this year it's been a matter of trying to slow the drift.
Last thing, Tim said the most important thing....persistence! Keep at it. You'll get on em at some point. Time on the water is all it takes.