Also, it might sound stupid, but make sure you run Windows Updates and install ALL security patches first. There have been some pre-auth kernel-mode bugs reported recently (as in last half of 2012) in the rdp driver which you really don't want getting exploited when you open up to the Internet.
Also make sure your computer doesn't have any accounts without passwords, that the guest account is disabled and that your other accounts have "good" passwords (i.e. not short or a dictionary word). Remember: If you can login remotely, so can anyone else who can guess your password - so make it hard to guess.