Double your dock lines and add chafing gear. Use all your cleats. Extra fenders dockside and off-side. Seal hatches with tape or clear silicone. Close through-hulls except the pump out-puts. Clean and test all pumps and auto-switches. Charge batteries. Remove or stow loose gear.
For more tips, check this post on another forum:
http://www.thehulltruth.com/boating-...cked-boat.html
Good luck!