When I built my first frame I got a book and taught myself. I told myself I'd make a hundred joints before I did the frame so I'd be used to it. After 70, they still looked awful, and I couldn't figure why. I was following the book as close as I could. I took my kit over to the garage of a friend who had retired from a career in welding for some tips. It was all he could do not to take the torch out of my hands as he watched me the first time. Turns out there's a big difference between the brazing described in my book (as in lugged brazing, not so different from sweating a water pipe) and the brazing I was trying to do (fillet brazing, known in other fields as braze welding). But my frame eventually came out just fine, and the thing that made all the difference was a little time with somebody who knew what they were doing. You ought to be fine getting a class from an expert.