To sell, we did both. We started with a few ads here, Craigslist, and a few other places (forums, local publications, etc.). And as to a plan we had from the start, after a few weeks moved to broker listings. Trust me, they will come out of the woodwork to get your listing. Pick one (or two) and have them either do a dedicated listing or an open listing on Yachtworld. The good brokers will list in several place. And while there is some validity to selling boats that are remote to the broker, I (and this is just a preference) would rather use someone local. A broker that will come look at the boat and be able to show it in person.
I would also reco that YOU write an extensive listing of not only the current condition of the boat, but all the work you have done and when. We even took our own pictures, but that isn't for everyone. Anyway, then let the broker choose what portion of the list and pictures their experience tells them will work.
In buying, the same thing applies. Do your homework. Find boats you want to see. I will be honest here, I don't always trust brokers (even someone acting as a buyer's broker) to always have my bst interest at heart. Call me skeptical, but that is just how I feel. I need the broker to negotiate with the sellers, be present during survey, and close the deal. There are some valuable searches they can provide, most especially for your first boat, but if you know what your needs are, you have probably narrowed your search to just a few boats.
Good luck.