I have trails that are really exposed too, so I know what you mean about the edge freaking you out. Just keep your eyes ahead and don't look down.

On switchbacks, look to the inside of your turn, don't look at the outside because that will send you off the trail. On a left hand switchback, try to start on the right side of the trail, look to the inside, use your new balancing skills and you should be able to pull it off. Opposite for a right hand turn of course.

Most people are stronger in one direction than the other. Practice extra hard in the direction that is not natural. That's where tiny circles and figure 8's in your driveway can help you.