Do not eat a pumpkin that has been carved as a jack-o'-lantern.
Choose a large pumpkin. The larger the pumpkin, the easier it is to carve. Avoid any pumpkins with bruises or moldy stems as they will spoil much faster. Pumpkins with a lighter color tend to be softer and easier to carve.
When cutting out the top, place the knife at a 45 degree angle so the the lid will have a place to rest when you replace it. If you cut straight down, the lid will fall through.
When cleaning the pumpkin, save the seeds. Toasted pumpkin seeds make a healthy as well as tasty snack. Use a large, heavy metal serving spoon or ice cream scoop to scrape the insides. If you will be lighting the pumpkin, the back wall should be scraped as smooth as possible since this is where the light will be reflected. A 1-inch thickness of the pumpkin wall is optimum.
For longer life, soak the cleaned pumpkin a couple of hours in a bleach water solution of 1 teaspoon bleach to 1 gallon of water. Dry thoroughly, then rub inside and out, including all cut edges, with vegetable oil or petroleum jelly to prevent shriveling. If the pumpkin begins to shrivel, repeat the process. The soaking time will depend upon how dried out the pumpkin has become.
Beginners should select a simple, bold pattern. Once you master the simple patterns, you can move on to something more difficult.
Print out or draw the pattern on a piece of paper. Use small sharp scissors or a razor knife to cut out the areas you will be carving into the pumpkin. Tape the template onto the pumpkin and use a marker to trace the carving lines. Cutting slits in the paper will help it to conform to the round surface.
As an alternative, you can tape the outline to the pumpkin and use a nail or large pushpin to score the carving lines onto the pumpkin. Connect the dots as you carve.
A long serrated knife or a pumpkin-carving knife with teeth will be necessary to cut through the thick flesh. Use a sawing motion and take your time cutting along the outside edge of the marker lines so there is no marker residue.
Consider cutting off the bottom of the pumpkin, as well as the top. The pumpkin will be more stable and also easier to carve. If you plan on using a candle to light your jack'o'lantern, be sure the opening in the bottom is large enough to fit over the candle. Place the candle on a fire-proof base large enough to accomodate the pumpkin. You can then easily lift off the jack-o'-lantern to light the candle.
If you will be lighting your jack-o'-lantern with a candle, be sure to leave the lid off to avoid any fire hazard. Use a votive candle in a glass holder or tea lights in a metal case. If you want to leave the lid on, carve a hole in the unseen back side of the pumpkin to act as a chimney. Never leave a candle-lit jack-o'-lantern unattended for any length of time.
A small battery-operated pumpkin light is a safer choice than candles for lighting your jack-o'-lantern.
Sprinkle the bottom side of the pumpkin lid with ground cinnamon, nutmeg, and/or cloves to let your jack-o'-lantern do double duty as an air freshener.
Place the jack-o'-lantern in a plastic bag and refrigerate when not in use.
Try making an uncarved jack-o'-lantern by painting on royal icing. You can enjoy a decorated jack-o'-lantern but still use the pumpkin when Halloween has come and gone.