It's a good idea to review the Installation material to refamiliarize yourself with the general process. Most importantly, review the ReleaseNotes carefully for any important changes you might need to account for or make. In general, you should not expect upgrades to require changes ahead of time, but security issues or other major bugs might occasionally require special care.
The upgrade process is designed to be very safe, and will never overwrite any configuration files, views/templates, properties, etc. that you have modified, except that any files in idp.home/system or idp.home/webapp are fair game and may be modified by any upgrade, so you should bear this in mind.
By design, the idp.home/edit-webapp directory can be used to preserve changes across upgrades, but if you modify an existing file (as opposed to adding files), you should always compare your changed versions to the upgraded files to understand if any changes are important, though we will make every effort to highlight any such changes in the ReleaseNotes.
Be aware that rolling upgrades are generally guaranteed to work only for patch upgrades (changes in the final digit). Minor upgrades may sometimes include internal changes to storage formats or other implementation details that could prevent certain features from working interoperably between versions. It is best to either plan for a relatively fast rolling upgrade within a maintenance window, or plan for a short period of downtime.
The installer available for Microsoft Windows handles upgrades from older releases. See thetopic for instructions. This also supports upgrading Jetty, if that option was selected.