I've sold 3 boats without a broker, but they were smaller ..22,24,28 ft.. A couple of things that I would add:
Make the boat look good. On the 22, it was like new for the most part, but on the trailer, the old bottom paint made it look ratty. I had the bottom painted and it looked like a completely different boat. Same with keeping it clean and hull waxed.
Keep the boat with for sale sign in a place with high visability of likely boat owners. In my case, this meant paying for storage vs. normally free storage.
Think about the questions that you would want answered and put these together in a handout with the boat's specifications and history. Include some pictures. Keep some in a plastic handout box at the boat, and also email these to those making inquiries.
Lastly, the number of pictures that you can post on most of the listing websites is limited. Set up an account on Photobucket, or other service, take a long series of pictures showing exactly what the boat looks like (good and bad...they are going to see the bad eventually, and if you initially hide that, they will be angry and not buy if they travel to look at the boat but feel they have been mislead). On the listing services webpage, include a link to the Photobucket site.
Get ready for some real screwballs, who will get angry with you in a minute if you refuse one of their silly requests or their lowball price. Also, watch for those who are looking for a free day's sail on the water for them and their friends by asking for a sail trial. But you need only one real buyer. Without having to pay a brokers fee, you have more room to fix up boat/negotiate on price. Make sure that your price is realistic, and include a little room for negotiation..maybe 10%. A little discount lets the buyer feel good about the deal that is being offered.