Cannot Connect Remotely to SBS 2003 or Workstations

So when using a client computer inside the LAN I can remote into the server as an administrator. What I would like to do from home is either just that, or remote in to one of the workstations at the office. I am fairly new to remote connections but always thought it was pretty straight forward. However when trying to remote in over the internet I have yet to be successful (aside from remote assistance). The server is obviously listening if I was able to connect at the office. What kinds of things would prevent me from connecting over the internet. Incorrect RDP setup from home? Certain protocols on the server? I was fairly diligent in making sure everything would be accessible on the server side…