In order: range, endurance, pitch, tonguing, sight reading. But I have to relativize, really. Never touched an instrument until age 26, but through hard work and lessons joined a little municipal marching band after only 18 months. Then quit playing for years and is now just 3 months back into real practice. So I guess that, everything considered, being able to hit a high C on a good day is nothing to sneeze at. If I don't see any good progress in a year, I will definitely seek help outside of the books/methods. Perhaps my biggest problem is life distractions and that nagging feeling that, no matter how hard I work at it (and if I work too hard I loose my lips!) I will never sound like those "real" musicians. You know, the kind who learned when they were kids and all... Love the site Rowuk, I especially enjoyed the "how a trumpet makes sound" thread.