My wife and I hired a captain for a day to provide us with docking instruction. It was well worth the price. I tried practicing on my own quite a bit as Faster recommended, but I really just ended up over-thinking it (too much good advice out there) and repeating my own mistakes. So sometimes having somebody knowledgeable standing by makes the difference.
If your broker can't recommend someone, then try calling Annapolis School of Seamanship and see if they can recommend someone in your area. You never know.