Show Grooming a Golden Retriever
I got started in dog shows shortly before covid took off in my area. Because of the quarantine, I learned so many grooming lessons the hard way before I found these resources. I hope I can give you some recommendations on some really amazing videos to help you learn. I am not affiliated with any of the products or resources listed here, they aren't mine, and I make no profit from recommending them. It's just what I've found to be really helpful in my journey.

Tips & Tricks
I have tried so many products and tips for keeping my Golden Retrievers in show condition. At the end of the day, I have found what works for us and have listed it below. Keep in mind, all dogs are different. We have another post that goes into more detail on products we like.
A high-quality diet that is formulated for Golden Retrievers and/or large breed dogs. I don't think there's a substitute for a well-balanced diet. Poor diets can be reflected in coat condition. We like Purina Pro Plan Sport. Some dogs do well on different foods, so discuss this with your vet and do what is best for your dog. Once you switch their diet or supplements, don't expect a change overnight. Give it a few weeks.
Salmon Oil - We add the daily recommended serving on the label of Zesty Paws salmon oil to our Golden Retriever's food. The dogs love it and we feel it helps their coat.
A Brush and Brushing Spray. Brushing your dog daily with a high-quality brushing spray is going to help prevent coat matting and help keep it laying in the right direction. It also teaches your dog grooming table manners by getting them on the table daily for short periods of time. Using a specially formulated spray helps prevent/reduce brush damage.
Weekly Baths - We bathe our show Golden Retrievers once a week. We only usually condition the featherings.
Show Grooming a Golden Retriever Videos
Watching an experienced person in the breed show groom a Golden Retriever in front of you is going to be one of the most valuable experiences. If you have a Golden Retriever breeder mentor who has shown their dogs and/or a Golden Retriever dog handler that can show you the ropes, that is going to be your best bet. There is no replacement for learning in-person, with your own dog.
That said, I know it is not always possible to have someone show you and sometimes you have to try to learn at home. If that's the case, I highly recommend the following videos and courses:
A Comprehensive Guide to Grooming Your Golden Retriever with Jennifer Hoffmann. This is a full course and I found it well worth the money. https://all-things-dogs-college.teachable.com/p/grooming-your-golden-retriever-with-jennifer-hoffmann11
BlueRose Kennels YouTube - This channel gives you a wealth of information about grooming, handling, and more. https://www.youtube.com/c/BlueRoseKennelsLLC
K9 Legacy Webinars - Ethos Golden Retrievers - These webinars are great resources for grooming and handling your Golden Retriever. https://www.ethosgoldens.com/freewebinars#upcoming-webinars