Making a Log of user activity in Solaris 10

My first post.
I need a simple way to log user activity to a unique file for each user and also if any user su's to root, I would like to capture that activity and have it in the unique file for that user.

what you want is called "auditing" in solaris... you'll find infos here:
Solaris Auditing (System Administration Guide: Security Services) - Sun Microsystems