Start by planning your picture. What setting do you want to be miniaturized in? Do you want to be posed with your pet? Maybe you would like an outdoor scene or a photo on your dinner table.
With Photoshop, you can "Extract" yourself or any object from the picture. Objects can be combined to create a new picture. (It's all in your mind!) Adjust the size, rotation, color or location of the objects in your photo to create something fun.
Let's say you want to pose with you cat. Have someone take pictures of you with a very simple background, a plain wall works best. Try several fun poses, pretend you are 6 inches tall and your cat is 12 inches high. Pose as if you are reaching up and grooming him. Turn your back to the camera, spread your arms out as if you were going to hug someone, then turn your head backwards as if you were talking to someone behind you.
Take several pictures of your cat also with a plain background. Try a picture of the cat standing and turning his head towards the camera. You will probably need to coax him or bribe him to get him to pose the way you want him. A picture of you could be standing under the cat holding him up over your head like a weight lifter.
Suggested Poses:
You are only limited by your imagination.
Many things have been made much smaller, cell phones, calculators and cars, so why not people?