I believe a good place to start is to familiarize yourself with the traits of the different breeds there are to choose from and to determine what might suit you and your needs the best. They are each quite different. For example, my neighbor has had and still does have a Great Pyrenees. Good livestock guardian, good with people and strangers, but this breed has a tendency to roam. And I don't mean over to the neighbors, I'm talking like 6 miles away. I've read about that in this breed before, and my neighbors
experience confirmed what I had read. He'd get phone calls from people miles away saying things like "missing your dog? he sure is nice and loves cookies!"
My neighbor is about to go get a Karakachan this weekend so he has two LGD's. Good guardian dog again, smaller in size than the Pyrenees, this breed is known to stay close to home, but also has a known tendency to not be good with other people and strangers. They'll bond to the owner, but that's likely it. They can show aggressive behavior to others. Maybe not the best breed if people are coming over regularly. I'm sure there are exceptions to every breeds known tendencies. I believe there is some degree of "nurture over nature" and spending the time up front with a dog will yield years of reward down the road.
Hope this helps! :)