A familiar is an animal bound to you. They are usually common pets like dogs, cats, birds, etc. Everyone has a familiar, or at least the spirit of one, but you can't just wait for it to find you. You have to be dedicated to finding it, and it will do the same.
Your familiar will help you with your magick, but you must train your familiar in your path. That way he/she can help you and lend you energy. However, please ask your familiar before you take energy from them, or else it's stealing. Your familiar will never leave you, even if you don't think you want him/her anymore. They will be devastated but will never abandon you.
There are a couple ways to get your familiar:
Doing a spell: If you choose to do this, I recommend a spell with more dedication, not one with just chanting.
Calling to your familiar: You can try speaking telepathically and see if you get a response. This doesn't usually work but it has in the past.
Make your pet your familiar: There are some spells on this site to make your pet your familiar. The thing about these is they're easy, but they don't always work.