Alright, I followed the cracks that were already in the wood and now have something a bit closer to staves, albeit sloppy ones. First pic shows the four splits I got, the rightmost and leftmost seem to be the ones to go for now. Narrowing it down to those two, I don't like how blurry the ring looks on the right one although it's off to the right side of it and it looks like there's plenty of material to work with on the left of it. The leftmost stave looks (to my uneducated eye) to be the best of the lot, the rings look regular and clean.
On all of them I can clearly see where the sapwood is a different color from the heartwood. So I should just knock off about the outermost three rings? (yeah, "just"! I'm sure it will be that simple. )