1. Prepare working Mini vMac and Basilisk II environment. Sheepshaver is known to have more incompatibilities in Extensions and applications. When your Sheepshaver system image cease to boot or some older applications crash in Sheepshaver you could use Mini vMac or Basilisk II environment for troubleshooting.
2. Never use QuickTime 3.x, 5.x and 6.x in Sheepshaver as they don't work as expected and might crash in Sheepshaver. In my experience Quicktime 4.0.x and 4.1.x are the best choices, and if there is no need for Carbon support or newer QuickTime features you can also try QuickTime 2.1 or 2.5.
3. If you want to use System 7.5.2-8.1 on Sheepshaver you need to use Old World ROM.
4. If you want to use Sheepshaver for Windows with router networking (The only method that need not to install any additional drivers on the host OS) you must not use Open Transport 2.x that come with OS 9.0. Instead, use older Open Transport 1.x.
5. If the sound output isn't working, try removing the "Apple Audio Extension".
6. 68k apps are more likely to crash in SheepShaver than PPC apps, so if an application has PPC native or fat binary, use that instead of 68k binary.
7. Some apps require much more memory when running in Thousands or Millions colors display mode than in 256 colors.
8. If you want to boot a Mac OS installer disc image without mounting it as CDROM, you need to remove the "xboo" resource in the "System" file from the installer disk's System Folder.