photo reference guide
Make sure the lighting is good - Try to get your pet out of the shadows or into light that shows their natural colors. If you have a pose you prefer in bad lighting, send a second photo to show the colors/details of your pet.
Send a High Quality Picture - High resolution photos show more detail. Use a smart phone or camera to capture your reference photo. Try to avoid cropping images or downloading from sites like Facebook for best results.
Get your model to give you a good pose - Try to capture your pet in the exact pose you would like painted. If you would like a certain goofy pose that is fine too!