I agree with jackcrafty. If you have a flat spot, you remove from just that spot. If you have a hinge you leave that area alone and remove would from both sides of the hinge until it bends uniformly. Don't touch the hinge spot until the hinge is gone. For me personally I typically make the arrow shelf about 1" above center but I think that is typically a personal preference thing. That works best for me, 1-1/2" works best for jackcrafty, you might like 3/4" better.
I would recommend getting the Traditional Bowyers Bible, great resource for bow building. The first thing they say about tillering & hinges/flatspots is remove wood where the bow doesn't bend enough and leave alone where it bends too much. So a flat spot is a spot that doesn't bend enough and a hinge is an area that basically has a flat spot on each side of it. At least that's how I try to think of it when tillering. But the main thing is go slow in the beginning and scrape the whole limb taking just a little wood in the time. You might think it's faster to just hack off a bunch of wood to get it into bow shape. But trust me if you go slow up front it'll be faster than spending time fixing the mistakes you've made.
