Upgrading LSF9 v9007 to latest LSF9 version

Greetings -

We are running Env 9.0.0.7.199 and App v9.0.0 PSP#4 on AIX,

Based on my provious upgrade, there were few items I had to prepare before the upgrade could take place, such as Oracle DB version has to be certified with the current LSF9, also AIX version has to be current. Lastly, not sure whether we can do Env. upgrade first, and then we can do App upgrade at later time, or do we need to apply both Env & App upgrades of the at the same time..

I am looking for answers to these questions as well as choosing the best approach to upgrade our current LSF9 version to the latest version hoping to plan my next upgrade effectively..

I was wondering if you performed a similar upgrade, and if you could share your experience  with us - Or if there are any links / documentation online that would help me plan my upgrade effectively, I would appreciate that..

Thank you.
-AJ