In my opinion, it is best to have one installation of Drupal core with multiple domains using that core installation. There is no need for symlinks. The Drupal installation instructions are pretty good. I was able to setup a multi-site installation without any issues.
This might be a good topic for a tutorial. I'll try to write one within the next week. Until then, take a look at the installation instructions at drupal.org and see if you can figure it out.