Things to remember when updating software:

• Backup what you already have
  
• Use checklists
  
• Read the documentation for the new software (including the INSTALL file and README) you never know what might have changed since the last time you did it
  
• When installing from source, (and who doesn't with security software?) run ./configure --help first and check the options available (they may have changed or new things might be available)
  
• Document what you are doing (what config options you used and why etc..)
  
• Make sure the new version is actually installed after make install is done
  
• Replace the old configuration file with the new one from your source tarball (no, really, this is important)
  
• Edit your new configuration to suit and document what you are doing and why (read your old config and notes, you did it last time right?)
  
• Test everything, make sure the software starts properly, logs properly and behaves how you expect it to etc...
  
• If the software is complex and puts a lot of files in different places on the system, it is also a good idea to start with a checklist of files that should be replaced, it might even be better to make deinstall the old version and make sure everything is gone before installing the new one
  
• If the software interacts with other daemons etc. make sure everything works as expected
  
• Keep a close eye on the system itself for a few days
  
• Take notes, the kind of notes that someone else could pick up, read and know what you did and could repeat or reverse what you have done