The Administrator Accounts Security Planning Guide has recently been posted to TechNet and hence is available for free download. It's a great place to start in reviewing how you manage privileged access. What ever type of user you are it's important to adopt the principle of Least User Access(LUA). Aaron Margosis has an excellent blog which focusses 100% on this very challenge. He recently posted an excellent article which covers the "why" and most useful "how" to run with limited privilege. Click here to read Aaron's article.
Remember one of the founding principles of information security "If you don't trust your administrators then you'd better get some new administrators".
The Immutable Laws of Security state this as follows "Law #6: A computer is only as secure as the administrator is trustworthy." Read about the Immutable Laws of security here