Keeping your copper pans in perfect condition after retinning
1.) Do not "preheat" copper pots
Since copper conducts heat so well, it heats up very quickly. The tin lining can and will melt in as little as 30 seconds depending on the size of the pan.
2.) Avoid scouring the tin
The tin lining will definitely change color over time. It will go battleship-grey to almost black depending on what you are cooking. You might be tempted to scour it shiny after every use - but that will greatly shorten the life of the tin lining. Keep it clean - but let it go. For cooked on foods, try filling the copper pan with water and a bit of dish soap then simmer for 15 minutes. You'll be amazed how easily the cooked-on food cleans up. Less elbow grease and less wear on the tin!
3.) Don't sear in copper pans
Remember, the tin lining melts at only about 450 degrees F. To sear meats at high heat, choose cast iron, aluminum, or stainless steel instead of choosing your copper cookware.
4.) Use wooden/silicone utensils with copper pots
Avoid scratching the tin cooking surface with metal utensils.
5.) Polishing 101
There are definitely two schools of thought here. Some love the bright look of polished copper - some love the soft tarnished "penny copper" look. Do YOUR thing; The copper will do ITS thing either way. If you are in the polishing camp - here is a great food-based polish:
Dissolve 1T salt in 1/2 cup of white vinegar, and add enough flour to make a thin paste (like Elmer's Glue). Store in a small Tupperware under the sink.
After washing the pan, dip a moist paper towel in the polish, wipe on the copper for about 30sec, then wash off with warm, soapy & water.
DRY WELL to prevent water spots.
If you do this after each use it will take about 30 seconds of extra time. Waiting six months and then polishing will require a lot more effort!