I'd really suggest you find someone who has experience in this sort of thing. However, as with any process it is determined by your business requirement and the staff you have to deal with it.
Processes have to have an escalation path etc. etc. but all of that is defined around your business so it's not quite so easy for us to answer not knowing your business.
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/