Do not overlook investigation at each third-party application vendor's site to see if they have comments, warnings, or updated application versions for High Sierra. If the site is unclear, shoot their support team an email asking about High Sierra compatibility. This information won't appear on roaringapps.
Make certain that you have all of the OS X El Capitan Security updates applied after 10.11.6 was released.
Check if your printer/scanner has High Sierra driver support at the respective vendor site.
If you are using Office for Mac, here is Microsoft's recommendation for High Sierra.
If you are currently using applications that require Apple's Legacy Java 6, then you will need to update that with Download Java for OS X 2017-001 for High Sierra.