Cartoonishness usually results from setting the ambient values too high in the texture editor. Also, as the others in this post have said, lighting is very important. Too much light can wash out the image, too little light can make everything look flat. It takes a lot of experimenting, but look through the galleries, and especially check out Dryfly's work, among others that post mostly Bryce images. And, some artists are trying to make cartoonish images on purpose, so you may want to keep that in mind, as well.

This is not my "second childhood". I'm not finished with the first one yet.

Time flies like an arrow; fruit flies like a banana.

"I'd like to die peacefully in my sleep like my grandfather....not screaming in terror like the passengers on his bus." - Jack Handy