Best practice is: back up your files, uninstall old FMS, then install new from scratch.
No way to install 'over it'!
Also keep in mind that FM13 is .fmp12 and FM10 ist .fp7, a new fileformat - test that before...
Check the requirements, maybe there's an update of the OS needed...
- throw all users out of FMS
- do a last schedule, just to make sure
- export/jot down settings, schedules
- close all databases
- stop FMS
- uninstall FMS10
- save the db's (just in case) on an external device
- migrate the db's using a FileMaker Pro/Pro Advanced
- do some tests
(the last two steps should be done as a test earlier, before stopping the srv, just in case...)
- install FMS13
- install the db's
- add schedules,
Long time ago since I migrated from 11 to 12... AFAIR, I saved the whole Server folder and deleted that to let FMS13 create all new, resp. on some machines, I installed that machine from scratch