The above tips on exposure are a good start - flash is not too flattering for many animals as they often have runny eyes or noses that reflect badly.
I've found if I put the cat on a table and make growling or hissing noises from behind the camera I can hold their attention for a while and they cannot get too close to you which is often the case if you sit on the floor.
http://www.flickr.com/photos/thedoctorn/2685190861/
If you hiss too more agressively you can get a startled shot like this!
http://www.flickr.com/photos/thedoct...n/photostream/
D