Fresh brake fluid and flush would be first on my list. Amazing how many people neglect this and its so easy, especially when the boat is off the trailer.
If you have a compressed air source, this kit from Harbor freight makes it too easy to not do it every 2-3 years.....
Otherwise get this one - http://www.harborfreight.com/mityvac...ump-39522.html
down side to the second is, it does not come with a fill bottle and accessories that makes for an easy one man job. Otherwise it helps if you have a buddy to pour fresh fluid in the reservoir as it is drawn out.
Once you are motivated, if you have a GM truck, do the brakes on that too. The Hydro boost system is hard on brake fluid! I could not believe how burned and nasty my fluid was at only 3.5 years old. GM now has it on their regular maintenance schedule for 2013 but all trucks built in the last 25 years should have it done IMO.
If a flush does not tighten up the brakes enough and you have drum brakes; time for some PB blaster on the rusty brake components followed by a good bath of brake cleaner.
Look up drum brake adjustment on youtube, and follow instructions.
Another way to test brake action - There should be a slot or lever on your hitch that will depress the master cylinder. Jack up the wheels and have a buddy spin while you work the slot with a large screwdriver.