We should, first of all, have the following in mind:

(a) The reason we want to adopt a dog (do we want a dog for protection, companionship, hunting? - at a shelter or animal welfare society we can find a dog that covers any of these needs).

(b) If we have adequate space for the size of dog we choose (if we live in a flat, a house with a yard or not, a farm etc). Not all breeds are comfortable in flat, for instance.

(c)If we have enough time to spend with the dog (our lifestyle). Cezar Milan, the famous Dog Whisperer, insists that a dog owner should daily share a minimum of 1 hour quality time with his/her dog (walking, exercising, playing etc).

(d) Our experience (there are, for example, breeds that according to experts should have experienced owners).