As soon as you can, eliminate the need for NIS-compatible NIS+ domains. Upgrading the last NIS clients to NIS+ will allow you to take advantage of NIS+ security features. You will not be able to eliminate the need for NIS-compatible NIS+ domains if you are running non-Solaris machines on your network.
When you have no more NIS clients, you can restart the NIS+ servers in standard mode and run nischmod on the NIS+ tables to change permission levels, eliminating the security hole caused by NIS compatibility. If you did not create credentials for NIS+ principals before, you must do that now. Restrict the access of unauthenticated principals.
Evaluate operational procedures to determine which ones can be improved, particularly procedures used to recover from problems. Plan for new NIS+ releases and possible functional enhancements. Track the development of Solaris components that might require new NIS+ tables. Look for automated tools that enable you to perform NIS+ administration functions more efficiently. Finally, work with internal developers to help them take advantage of the NIS+ API.