Remove old, rusted nails. This will be difficult because when the nails were first put in, they were curved back into the trunk. Try to find the curved end and cut it off using the end nipper pliers. Use the tack lifter to pry the head of the nail up and then use the regular pliers to remove the nail.
Refurbish or replace rusted tin. Remove the metal pieces. For small areas of rust, remove the surface rust to a matte finish with wire wheels on an electric drill, sandpaper and wire brushes followed by steel wool. Paint on a clear protective coat.
If the tin looks as though it has been submerged in water for some time, more drastic measures may be in order. Extend Rust Treatment is a product that you can find in auto parts stores, and it kills off rust and turns it into a black, paint-ready surface. After treatment, prime with any primer intended for steel, and then paint the piece with a satin black paint.
Any tin that is completely rusted should be replaced with new tin or aluminum sheet metal. Cut the metal to fit and nail in place.
Clean canvas coverings. If your trunk has an intact canvas covering, re-glue the areas that are loose with white glue. Weight it to clamp those areas flat until the glue dries. Clean and repaint the canvas. Preserve with a clear coat. If the canvas is in bad condition, remove it. You can replace it with new canvas, or you can leave the wood exposed and proceed to step 5.
Restore leather coverings. If the leather is in good condition, use saddle soap and a soft cloth to clean it. Restore the suppleness with neatsfoot oil. Re-glue loose areas with white glue and weight the areas down while the glue sets. If the leather's in poor condition, or you'd rather have the wood exposed, remove the leather and proceed to step 5.
Fix up wood slats. Strip any paint off the slats with a paint scraper and clean with furniture refinisher like Murphy's Oil soap. Sand the slats and re-coat them with tung oil or any top coat you choose. If you want to refinish the slats, use an oil stain and an oil-based top coat.
Replace the nails and the metal pieces. Hammer the nails from the outside while holding a steel heel against the wood on the inside of the trunk. This way the nails curl over on the inside of the trunk and are holding the metal pieces on the outside tightly.
Reline the inside of the trunk. The usual materials for this are plain paper, wallpaper, decorative paper, fabric and cedar paneling. Wet the old paper down with mixture of vinegar and water, then scrape the paper off using a paint scraper. Cut each piece of material to fit with 1/2" extra at the corners (to overlap where the edges meet). Reline the ends first. Then reline the front and back, and then reline the top and bottom. Make sure the wood is sealed and use white glue to paste in the material you're using.