Taking the photos at eye level is ideal so that I can capture their full facial expression. Try to get your pet to look straight at the camera. Watercolor portraits primarily depict just the head and neck, hand-drawn and digital portraits vary.
Photos that are high-resolution produce more detailed portraits. Try to take your photos up close and be sure they are not blurry. Images from your phone or camera are best as images from social media are often very small and sometimes pixelated.
Natural light during the day is the best way to light your photographs. Images that are too bright or too dark will lose detail.
Be sure not to crop out parts of your pet's ears or face and if possible, take off their collar before starting so I can see their neck..
Gather your pet's favorite treats and/or toys and find a quiet, well-lit area with few distractions. Ask your pet to sit and stay if they know the commands. Get down on their level if you are able and hold a treat or toy high enough so that their face is looking at the camera. Try to hold their gaze with the treat or toy. Say their name in a high voice if needed. Once you've taken a few photos, reward them with the treat or toy.
Try to capture photos that show your pet's personality. Although I can work with photos of pets sleeping, images that depict your pet's usual expressions tend to make for better portraits that really portray who your pet is.