If you walk around the grounds at a dog show you will eventually hear conversations about what product is the best for what breed, and eventually you just HAVE to ask what a person is using because the dog looks amazing. If you're really lucky you get to stand by and watch while a groomer prepares a dog for the ring and pick up tips and tricks to use yourself.
I've tried many, many products on my longhairs and the ones I like the most so far come from an Australian line called Plush Puppy. I start off with the Natural Conditioning Shampoo to condition and detangle and then condition with the Natural Silk Protein Conditioner. A good tip that I just tried was to mix conditioner with your shampoo for extra help detangling and conditioning the coat. Tried it yesterday on Ernie and it works great! After they are rinsed out completely and before they are ready to be dried I put on a dab of Swishy Coat to help flatten out the coat along the back and the sides and to help the ears and feathering "float" a bit more. Right before we go in the ring I spray a bit of Shine and Comb to make them extra shiny which helps on black dogs especially when you're inside. Another line that I've heard rave reviews about but haven't tried yet is from Isle of Dogs.
But try out different lines and see which one is the best for your breed and its coat. Ask around and see what other people like to use and what does and doesn't work during different times of the year. Often you'll need to use different products and different techniques on the same dog depending on the coat. If you can get a few friends together see if a dependable groomer will give you a private lesson on grooming your breed to bring out its positive aspects while "hiding" the negative. It's amazing what you can do with a pair of scissors! If you keep up with your daily or weekly grooming you'll have less hassle when it comes time for a thorough session. Nutrition also plays an important part in the health of the coat, provide the highest quality food you can afford.