Once you give notice, promote yourself and build relationships throughout the organization. This is especially important before you leave. After you're out the door, your efforts might not be warmly received. Start thinking of your organization as a client. Consider ways that you can bring value to your new relationship.
Consultants bring sharper insights, often unjaded by organizational politics.
Deliver more truth and greater perspective. Being an independent contractor involves significant risk. Be prepared to trade risk for potential reward, even if it doesn't come overnight. Most important, be certain you're choosing free agency for the right reasons. Moving on is a big step.