I raised and trained police (and just regular) dogs for nearly half my life. I also volunteered at a local shelter. So I know a thing or two about dogs. So if you're looking to get a dog, I highly recommend you go to an animal shelter. Why? Because there are dogs of all age, sizes, and breeds there. Don't go there having your mind made up on a certain type of dog. Half the time the person walks in wanting the dog we were holding for them and ends up with a different breed altogether. The dog chose them.
Not only are there many types of dogs all in one place, you know they're up to date on their shots. Also you have experts there to answer any question you might have honestly. These people aren't out to sell a dog for profit.