Just my take..... Cutting: Sharp blade, and go slowly. Try to avoid cutting inline with any cracks/checks. Drilling: Same, new/sharp bits. Some like to drill it on high speed, others low speed. Personally I always try to drill at higher speeds but with a VERY slow feed rate, from what will be the exposed side, otherwise I always seem to get chipping where the bit exits. Sanding and polishing:......TAKE YOUR TIME. When fossil ivory gets thin, it warps easily from sanding heat.....if it gets warm to the touch, set it aside and let it cool naturally. DO NOT get in a hurry and dunk in in water! That makes it warp even more. Normally what happens to me is it always warps (cups) towards the side I sand on (doing it on the machine). If I have to get really thin, I do a lot flat side sanding by hand, one a granite plate. Its a lot of work, but it doesn't warp.
I've found that fossil ivory doesn't like the flat bottom counterbores, when I try to do it that way, I always get tiny chips all around the perimeter of the counterbored hole..... just drives me nuts. I tend to use a standard 135 degree drill bit for counterboring fossil ivory.....don't get the chipping around the perimeter of the hole that way.
Those are just some of the things that come to mind. I've talked to a lot of makers about how they think fossil ivory is best worked, and each seem to have their own unique methods for working it.