General rules for taking a good resource photo
1. The lighting should be as you want it to appear in your finished work (avoid flash, unless you have another source of strong light as well. Then use the flash to fill in the shadows.)
2. Detail in shadows if you need have it for your piece
3. Interesting perspective.
4. Photo is in focus
5. Shoot at least three shots of your subject with different exposures (bracket).
I. For an animal portrait
This artist has some incredible pet shots. You may not use photos from the internet. You must take your own.
Notice how she lights her image from the side, yet the shadow side also has detail.
This site gives some awesome hints on how to shoot pets.
http://www.digital-photography-school.com/how-to-photograph-pets
II. For an human portrait
III. For a landscape
IV. For a still life