Find one or two groups that like to work with new technology and roll out SharePoint just to those groups.

Ensure that your users have received collaboration training on how to work with documents in SharePoint.

Train a sub-set of your end-users to be SharePoint Power Users (or whatever title you want to give them) who can effectively administrate and secure major portions of your SharePoint deployment, including site collection administration.

Have a serious discussion with your legal team about the potential problems of having the different types of information exposed to the wrong people and how that information should be managed.

Information security policies should explicitly call out how documents are secured within your SharePoint environment and who is responsible for securing them. Penalties should also be called out in the policy and then enforced when broken.

Have an organization-wide information architecture from which document-type definitions can be described and then implemented in SharePoint.

Map out your information types and then communicate how these types should be managed within SharePoint.

Do not allow your users to use the SharePoint technology without first receiving training on the proper methods of use and administration of a SharePoint site.