Going to dog shows is a great way to meet breeders. Wandering around or hanging around the Labrador ring and showing interest is good. Just be brave and tell them you are interested in a pet Labrador in the next few months, or whatever your time frame is. Most people are pretty friendly around a dog show, especially Labrador people. Just be polite and ask if it is a good time to talk dogs with them, or ask for a business card, to break the ice. The all breed shows move along pretty quickly, people usually show up a half hour to an hour before ring time to prepare to show, then disperse pretty fast after judging is over.
Here is a good way to look up shows.
Infodog is a popular informational dog show website, there is even a search function to find shows in your state.
InfoDog AKC Dog Show Information - Search by State
Choose your state (I chose Maryland)
InfoDog List of Pure Bred Dog Shows Held in MD
Choose a show, I chose a conformation show, because that's what I mostly compete in, if the show is already closed, (usually closes 2 weeks before a show) you can click on the kennel club,
MB-F Show # 322 Upper Marlboro Kennel Club, Inc. - Sunday November 23, 2014 (The Marlboro Kennel club show tomorrow in Friendship is the example I used)
then click on the Judging Program to look up when Labradors show and what time.
Labrador are listed under
Retrievers (Labrador), you can see the the number of entries, ring number and time; 22 dogs entered, Ring 8 at 8:30 am.
https://www.infodog.com/jps/322/jpg322.pdf
Most rings are marked at the top of the tent, or on a pole, or you will see Labradors set up near the ring. You can buy a catalog the day of the show to follow the classes and see the registered names of the dogs, etc... Depending on the venue, there may or may not be food vendors, or chairs, so bring food and a chair of you want to sit to watch. Mist decent size shows have vendors with all sorts of fun dog equipment and toys, grooming supplies etc...