I am still a beginner. I have 2 working bows, one I hunt with. Just finishing a 3rd--all with boards, never a stave...yet. I've read exenstively about reading grain on suitable boards for bows, but experience is the true teacher. I thought I had a great piece of White Oak, then, when I pushed her to over 50#, she exploded. I studied the break and finally made the connection about bad grain and grain "running off the edges". The worst part, is that the bad grain was always there and I was naive evough to think other aspects of the board would save it. Nope--when it comes to boards, grain is king.
TBB2, I think, has the board bow section and it's extraodinarily helpful, so I'd study that section. The bent stick advice about boards is helpful as well. And the single best place for advice is right here in this forum.
Good luck!
-Bri
One good thing though--all my 9 mistakes so far cost me less than $70...try that with staves! (I can't get my own--large city livin here).