it took me about 6 bows to get a shooter, and have made about 20 since then with a few breakages mixed in. some of those 20 turned out real nice but i think i got lucky with them. Only recently does it seem like things have "clicked", now tillering is easier, knowing how wood reacts to my tools, etc. This has all been with straight limbed longbows, don't mix in the "extras" like recurves, sinew, etc till you really get the hang of just using your tools and making a shooter, then you can advance your skill. Just my thoughts, keep at it!
Oh and one more thing...TILLERING GIZMO!