5) Try to cook acidic product in another pan then one tin lined.  Example tomato sauce is high in acid.  We use acid to strip the old tin off; tomato sauce does the same thing at a slower process.

6) To help keep the "fresh polished" look we use two products.  First the polish "Wenol", it comes in a red tube, a little goes a long way with this product.   Next we use the  polish "Wrights", we like the "brass polish" for copper items.  We prefer the liquid form.