Zenmagick is correct. Your familiar has to choose you, you cannot choose it. If it's a physical familiar, it will normally be a pet rather than a wild animal. If it is not physical, you may meet them in the dreamtime or on the Astral.
Spells to conjure or make a familiar are fake. They are filled with false information.
I agree with Sterben5. I do believe it'll be easier to find your familiar, or Spirit Animal in the astral plane, although I don't know if you can astral project.
Familiars are animals that aide your in your magickal practices. They help you seek guidance. They can appear in many different forms in your dreams. Any animal can be your familiar. Rather its a cat, a frog, snake or an owl. But like others say not all familiars have to be physical, as in here in pyshical form on earth, but also on the astral/spirit planes. They come to you when you are ready to see them. But not everyone believes in familiars or needs them.
I'm not sure where the idea that a pet is the same as a familiar came from. I guess I have to blame it on some of the crop of poorly researched books on the market these days. But the fact of the matter is that our beloved pets and a Witch's familiar are very, very different things.
A Witch's familiar is an animal spirit or a magical construct created by the Witch or the Magician as an adjunct to their magical workings, as a repository for power, and if needed as a defense against magical attack from another magic user. A Witch or a magician can draw upon the energies of the familiar when they need an extra boost of energy in a magical working. Conceivably if the spell is important enough, the Witch could completely drain the familiar of energy causing it to "die" or cease to exist. And in the case of a magical attack, the attack could be diverted to the familiar so that it would be the familiar which is destroyed rather than the magic user. None of these are things that I think any of us would want to do with our pets.
There is an excellent article on familars here: http://en.wikipedia.org/wiki/Familiar_spirit
Animals are very sensitive to the energies around them and they may be drawn to us when we are working magic because they can sense the energy. They also want to be around their people, which again will make them want to be where we are..and that may be where we are doing magic. Neither of these things makes the animal a familiar or inherently magical in and of itself.
Lark, from personal experience, I can tell you that you're *mostly* wrong. Pets CAN be familiars. My familiar is a pet, and yet she helps me in my magic works in the Earth Element and has traveled with me in the Astral. She's even visited me in the Dreamtime.
I have five pet snakes, But yet only one of them is my familiar. I have three cats as well, but they are not my familiars.
I did not even buy her, really. I won her in a game when I bought a different snake of mine.
familiar means a familiar spirit as in a spirit with which one works othent so you can not go get one with a spell dude, movies i swear they are killing peoples concept of magic =