A good way to get rare pets is to have been around the site for a long time
![Smile :)](./images/smilies/icon_e_smile.gif)
that's how i got most of mine, since many of my pets from 2 years ago are now considered rare. Also the holidays and special occasions tend to be times when some of the most desirable pets are released. So my advice is to try and pick up any pets you can and to not miss any and you are bound to end up with some rares eventually! Or you can always trade of course.