My biggest tip would be to try and find owls yourself. If you are familiar with their habits and habitat, and spend enough time in the field, you will come across owls from time to time. Particular tips I would give are:
-Let other birds find them for you. Crows going nuts might indicate they've found a Great Horned Owl, or a Red-tailed Hawk, or a Fox etc. Similarly, chickadees become very agitated in the presence of Saw-whet Owls, Screech Owls, Sharp-shinned Hawks and to some extent larger predators like Long-eared Owls.
-Check small to medium-sized dense conifers, especially ones near open fields. These are ideal locations for roosting Long-eared and Saw-whet Owls. Often the whitewash (poop) and pellets below are more obvious than the owl itself. Just be considerate as owls can be very easy to flush. Don't get any closer than you need to be to see it, especially if it opens it's eyes and starts staring at you. This isn't always possible of course. The last Long-eared Owls I saw were three I flushed from a cedar without having any clue they were there - I was looking at a rabbit carcass nearby!