Think of canning as a precision form of cooking. You will use ordinary kitchen skills but must observe instructions exactly to ensure that the food is sterilized and safe. This is one time when you definitely shouldn’t improvise.
Selecting jars and lids
Use mason-type jars, which come in a variety of sizes. Pints and quarts are common and suitable for most canning. Choose from easy-to-fill wide-mouthed jars or traditional-looking narrow-mouthed jars. You can either start with new jars (they cost less than 75 cents each) or recycle previously used but still perfect (no cracks or chips) canning jars. Avoid mayo jars and other kinds of glass containers because they may not hold up to processing.
The lids used for canning consist of two pieces—a flat metal disk (rimmed with a rubber gasket) that covers the jar opening, and a screw-on band that holds the disk in place. Always use new flat metal disks because the gasket around each rim can begin to deteriorate after sitting in storage for 5 or more years; consequently, it may fail to seal. You can reuse screw-on bands, though, as long as they look good and have no rust.
Wash lids and jars in hot, soapy water—either by hand or in the dishwasher. Then sterilize the lids by submerging them in hot water and boiling them for 10 minutes. Remove the pan from the heat but leave the tops in hot water until you're ready to use them. Do the same for jars that will be processed for less than 10 minutes. Use jar lifters to handle the hot jars.
Slice and dice
Start with top-quality fruits and vegetables, and avoid any that are overripe or blemished. For maximum vitamin retention, process produce immediately after it’s harvested. Wash well and cut into pieces as specified in each given recipe. To prevent browning of fruits such as peaches and pears, keep them in an ascorbic-acid solution (available where you buy canning supplies) after you slice them. To keep produce from discoloring once it is canned, during preparation do not use any bowls, cookware, or utensils made of aluminum, copper, iron, or chipped enamel. And if your water is hard, use soft bottled water to prepare the food and to fill jars of produce.
For more information and delicious recipes, here are two great resources on canning and preserving: