I won't fish dries in a lake unless I first see trout rising. Then I will attempt to drift within casting distance and cast to a specific fish, to the spot where I think it will be looking next, based on its last couple of rises. No way will I cast out a dry blindly when I see no fish rising. Just ain't gonna happen.
But at dusk, during the "evening glassoff," if trout are rising, or any time you see trout rising, try it. It's a blast when a trout grabs a fly off the surface and then immediately explodes into topwater action. Most of the jumpin'est trout I've caught have been on dries.

As far as trolling, I love my electric, but I often set up a wind drift where I occasionally blip the throttle to control my drift, or even put it in reverse to slow down (in lieu of a drift sock). I'll make alot of turns, free drift and strip in, haul my line out and cast it to structure or weeds or along the dropoff as I drift slowly by. I will correct my course to be sure I'm drifting exactly where I want my fly to go...Very active trolling. I'm standing up alot of the time. To fish like this, I must go alone, as I can't fish this way with someone else in my boat.

To see a really good pic of a primo Callibaetis Emerger pattern, go to the WA flyfishing.com website forum and search for Preston's "Chopaka Emerger." Its back on page 3 or 4 (in the flyfishing forum) by now, in a thread on "Stillwater Patterns."

I also use a sonar to figure out the lake bottom. When I fish a new lake, I "map it out." I go around the shoreline. Then I crisscross the lake several times in a loose grid pattern and pay attention to dropoffs, weedbed covered shoals, submerged woody structure, rockpiles, old creekbeds, and any other thing that might influence where the fish are. And make a mental note of it all....for future reference. This is on smaller lakes...big lakes are just too big to map out the whole lake and remember it all.
My sonar has been an indespensable tool...an absolute must for figuring out lake bottoms. I wouldn't want to fish a new lake without one (but I'm sure that I could succesfully, as I have done so in the past...just spoiled now).

Its a never-ending learning experience, thats for sure.