Don Geary's welding book is pretty good. He suggests starting with O/A brazing first then O/A welding. There are a bunch of good exercises in there to teach puddle control and other good stuff. There is a link to the book on my website: http://tinyurl.com/littlebluetractor
I got pretty good at O/A welding by the time I used up my 3rd tank of acetylene. For light gauge steel it is a very efficent process and way more controllable than stick or mig on sheet metal. I've welded 3/8 thick steel with O/A, but it isn't the best way. Big torch tips use up a lot of gas and the whole workpiece tends to get hot, not just the area around the weld.
