Remove all canvas from the boat, including sail covers and sails. If you have a
good mooring, put the boat out on it. Heavier lines are pretty much useless and I would discourage there use. The reason for this is heavier lines stretch less..and you want stretch capability to ease shock loads on the boat AND it's cleats. Nylon lines are best.
The MOST Important thing you can do is make sure you have "chaffing gear" around the lines where the lines pass over the side of the boat or through chocks. Chaffing gear can be anything from scraps of canvas or rags wrapped tightly around the dock lines or mooring pendant and lashed onto the dockline..etc. You don't want the chaffing gear to move relative to the line, or the line will chafe Inside the chaffing gear.
I am not a big fan of the store bought "Rubber" hose type things, although they are better than nothing.
Bottom Line: NO Canvas left on the boat. Plenty of Chaffing Gear. Out on a Solid mooring if you have one. Extra docklines if at a dock AND plenty of BIG Fenders.
NB
PS: "Fenders" are those rubber thingys that some people leave dangling over the side at all times because they look totally nautical. Some people call them "Bumpers"
EDIT: Many boats today have "Self Bailing" cockpits which is a BIG Plus. Self bailing does NOT refer to Pumps, but rather the capability to drain water overboard that enters the cockpit. If you dump a bucket of water into the cockpit, it will either run into the bilge (Not Self Bailing).. OR.. it will run out the back through holes or openings near the transom. (Self Bailing).