I would say that it really varies in what type of environment this company is in. I know with the company I work for, we force the rules upon people. Which is almost what you have to do, in order to get everyone on the same page. Things such as:
-file sharing over email
-password lengths
-downloading files
-installation of applications/games
-playing games
-access to certain files
-access to internet sites

Are all controlled by myself and the other net admins (this is a large company). We've found that the best way to communicate them however, is through our corporate intranet site. Everybody's browser is set to goto the website on startup, we've set rules so that the user cannot change this setting, therefor, anything new as far as policies or company news are viewed everyday by the users as soon as they open up the internet browser.

But even before that happens, we have meetings with some of the corporate bigwigs, to see if these are acceptable to each respective department, and then our own internal meetings for brain-storming the best way to deploy and manage these policies.

In my opinion, the best way to make a user obey the rules, is to take away the choice of breaking them. (although they still try ) But we all do sometimes....

Cheers