First off, frustration does not help. You can't fight what you're doing or your problems will only get worse. If you don't see signs of improvement, you need to step back to figure out why. And if you can't figure it out yourself, ask for help. I asked my affable instructor, Greg Smith, for his sage advice. He told me to get my ducks in a row. In this case, I should check all my reference surfaces to make sure they were flat and square and make sure that my tools were sharp, very sharp. I learned that I need to think systematically about where the problem might be, not assume that I'm doing something wrong. As it turns out, the problem is normally in the tool!
Yesterday was somewhat better. I spent the day getting my ducks in a row--organizing my space and tools to create a good work flow and sharpening, sharpening, sharpening. After school I went to the pool where I ran into an impromptu swim team and then met Greg's chickens. He sent me home with two eggs, which I ate immediately. I feel much more ready to get through my half-blind dovetails and through mortise and tenons today. Thanks, Greg! (And thanks to Dixie and Professor Chaos for the delicious eggs.)