How is your ServiceNow instance running? Here are some checks you can do to insure your ServiceNow instance is staying in good health.
Review User Accounts
User Accounts. Are the user accounts correct? Should these users have access to ServiceNow? (https://instance.service-now.com/sys_user_list.do?sysparm_query=active%3Dtrue%5Esource!%3DNULL)
Local Accounts. How many active local accounts do you have? Should you have local accounts? A local account is one that doesn't come from Active Directory, Okta, etc and has the password stored in ServiceNow (https://instance.service-now.com/sys_user_list.do?sysparm_query=sourceISEMPTY%5Eactive%3Dtrue)
Licensing. How many licenses do you have for ServiceNow Licensed access. Do the users fall under that limit? (https://instance.service-now.com/sys_user_list.do?sysparm_query=active%3Dtrue%5Eroles%3Ditil)
User Licenses. Check Licensed User Accounts that haven't logged in in over 60 days (https://instance.service-now.com/sys_user_list.do?sysparm_query=active%3Dtrue%5Eroles%3Ditil%5Elast_login_time%3Cjavascript%3Ags.daysAgoStart(60))
Admin Users. Review admin users and remove unnecessary access (https://instance.service-now.com/sys_user_list.do?sysparm_query=active%3Dtrue%5Eroles%3Dadmin)
Service Accounts. Review access and rights for Service Accounts
Find Stalled Tasks
Open Tasks with Assigned to Deactivated (https://instance.service-now.com/task_list.do?sysparm_query=assigned_to.active%3Dfalse%5Eactive%3Dtrue)
Approval on Closed Tasks (https://instance.service-now.com/sysapproval_approver_list.do?sysparm_query=sysapproval.active%3Dfalse%5Estate%3Drequested)
Approver is deactivated (https://instance.service-now.com/sysapproval_approver_list.do?sysparm_query=approver.active%3Dfalse%5Estate%3Drequested)
Caller is deactivated on incidents (https://instance.service-now.com/incident_list.do?sysparm_query=active%3Dtrue%5Ecaller_id.active%3Dfalse)
Requests with Requested By is deactivated (https://instance.service-now.com/sc_req_item_list.do?sysparm_query=active%3Dtrue%5Eu_requested_for.active%3Dfalse)
Deactivate Unused Applications and Functionality
Deactivate Unused Applications
Deactivate Unused Modules
Deactivate UI Actions, related lists, and functionality that don't want being used.
Errors and Issues
Request Stages properly set and Requests being closed at end of request
Work Queues show correct and appropriate tasks
Incidents being closed properly
Check the error, warning, and script logs for errors
Check stats.do for memory or performance issues
Infrastructure and Data
Mid Servers up and operational
Discovery properly discovering CIs without errors
ServiceNow Version is up-to-date and patched
Check Table Row counts for large tables
Look at Table Rotations to insure correct tables are rotated correctly
Deleted Records table is correctly adding appropriate records to deleted records table
Look at tables for Duplicate Records
Check Reports and Dashboards for load times
Expired KB Articles and Feedback
Check for blank or bad homepages
Coding Practices
Check number of update sets and update set naming convention
Look for Descriptions in Update Sets
Check Default Update Set for high number of records or admins using Default update set
Review Code Migration Procedures
Tasks Created in Development instance. If you haven't locked out users from your Sandbox, Test, Dev, UAT instance, you should check to see if they are still using Production like they should.
Interfaces
Check number and types of interfaces used in ServiceNow
Review Transform Maps and deactivate unused maps and maps without an import set
Review Scheduled Jobs
Hope that helps,
Mike