Developing an ideal yearly patching strategy for EBS R12.1.3

The client has upgraded to R12.1.3 in Aug-13 from 11.5.10.2Apart from applying the recommended GDF patches/scripts mostly for AP module no major patches have been applied in the instance. The client would like to come up with a patching strategy that is helps enhance the stability and performance of all the installed applications. The proposed patching strategy should have minimal disruptions to the business operations and any major family patches etc that need extensive testing is anticipated to be performed only once a year on need basis so that the critical business operations are not disturbed.
We would like to understand how to verify what all latest patches that we need to apply assuming that the current system is working normal except for normal support issues. As of the date of raising this SR there are no critical issues identified that will prevent any of the subledger or GL to be successfully closed.  That being said most of the issues that are frequently encountered are in AP module that has seen new or old GDFs being applied every month since go live. The customer would like to focus on getting majority of the AP issues addressed