When I was working on a couple of ships a few years ago, (Cutty Sark and Charles W. Morgan) some of the references I used said that the Americans coppered from the keel up, whereas the British coppered from the waterline down. Don't think it makes a lot of difference in appearance, but if you're a purist. I also polishsed my copper after I'd finished and then coated it with a spray lacquer. Over the years they were on display, I never had any discoloration.
I'm a stained glass artist, so I've used a lot of copper foil in creating Tiffany style pieces.
Don't buy your copper foil from ship modeler's websites, go to the stained glass ones. I've used www.Delphiglass.com for a lot of my supplies, but there are many and Delphi isn't the cheapest.. Copper foil comes in a variety of widths generally from 5/32 to 1/2 inch so you can match the width of the foil to the scale of the ship. It also comes with a variety of backing colors. I typically use black backing for my stained glass, but it also comes as copper-backed and silver backed. My recommendation is black, since, should a corner come up it would show black which would resemble the felting and tarring used under copper sheathing. The copper also comes in a variety of thicknesses. 1.0 and 1.5 mil are the most common. I prefer the thicker copper since I feel it's easier to detach from the backing paper. Copper sheets with black backing and adhesive are also available if you need odd shapes.
Delphi--and all other stained glass vendors--also have some useful tools. THey have very nice burnishers, which I use to make sure the copper foil is firmly attached, but also use it on my masking tape to avoid paint leaks under the tape. They also have fids, which may be useful it moving small things into small places, or making sure that the copper fits tightly into a groove.
Probably the most important thing for me is a foil dispenser. When foil starts to come off its spool, it makes a terrible mess of copper tape all over the floor that's creased and you can't do anything with it. Think 'toilet papering' a house. Obviously the dispenser shown at Delphi is made for a number of different sizes. In my stained glass studio, I'd occasionally have all six slots filled with different widths of copper foil. An alternative would be to one of those paper towel holders, but I'd put another layer of something down on top of my spool of foil to make sure it didn't fall apart. The other thing that can/should be done is to leave the spool in it's plastic wrap, and just pull out what you need.
Finally, if you need strong strips of something, look at 'strongline', which is a thin 20 mil x 1/8 strip of spring steel coated with copper. If I needed strong pintles and gudgeons ore chain plates, I'd think about using that product.
I also use the ponce wheel method of making 'nails'. Just make sure to impress the paper side, so the point of the wheel doesn't go through the copper.
After the ponce wheel, I detach a length of the backing and cut my pieces to the right length (5/8" for me) and apply them directly. I use narrow masking tape to keep my copper lines straight.
Hope this is useful. I'll be starting a blog soon on my current project USF Essex (model shipways)