Make sure your candle burns evenly the first time you light it.

When you light a candle for the first time, let it burn for a while. You want to ensure the entire surface of the candle melts before you put it out. If you don't, your candle could end up with a rim of solid wax that never ends up melting. (This is called tunneling—and you've probably seen it happen.) If you want all the wax in your candle to burn, let it burn evenly before you put it out.

Keep your candle clean.

Once you've used a candle a few times, you may notice that soot and other debris have accumulated inside the container. Clean this gunk out the moment you see it. Debris that protrudes above the wax can be ignited by the candle's flame and produce multiple flames in the candle. Use tweezers (or something similar) to pluck wick trimmings from your candle's wax whenever you see them. Use a dry towel to wipe away soot, fingerprints, and other aesthetic distractions. (Don't use a wet towel, because water can disrupt your candle's burn.)

Trim your candle's wick.

If you want a clean, even burn, make sure your candle's wick is the right length. This might require some trimming. Before you light your candle, double-check your wick's length. If it's longer than the recommended 0.25 inches, use scissors (or a wick trimmer) to neatly trim it. Try to be as precise as you can. A too-short wick can get lost in a sea of melted wax and fail to light.

Retire your candle while there's still wax in it.

You should stop using a candle before it completely runs out of wax. Why? If you let your candle burn all the way down, it could overheat its container—which could damage the container, create a mess, or both. Most candle experts recommend retiring your candle while there's still 0.5 inches of wax left in it.

Remember, you can always clean out the wax and reuse your container. It is recommended to use a mug warmer to burn off the rest of the wax or place your candle in the freezer. This can cause the wax to shrink, allowing you to get it out more easily. Give your vessels another life and reuse them for other purposes—as a flower vase, an orchid pot, a pencil holder, or a makeup brush holder.

Store your candles in a cool, dark place.

Unfortunately, your candles can expire over time. And while they're unlikely to spoil the same way food does, they can lose their fragrance, become discolored, or otherwise grow stale. Temperature fluctuations can speed the aging process up—and light can, too. Find a cool, dark place to store your candles between seasons.  And whenever possible, try to light your candles within 12 to 16 months of buying them.

Do let your candle burn for about 3 to 4 hours at a time.

One of the most common candle mistakes: are people letting their candles burn too long—or not letting them burn long enough. Candles are developed to be burned for three to four hours at a time. So you'll want to get as close to this burn duration as you can.

If you go too short, your candle may tunnel, or it may not smell very fragrant. The fragrance is emitted via evaporation from the pool of hot wax. So the larger the hot wax pool, the more it can emit. If you go too long, your candle may get too hot, and its wax may get too thin. The heat can damage some of the fragrance oils in your candle, and the thin wax can cause your candle to put off soot.

Don't put your candle in a windy spot.

Wind can cause your candle to burn unevenly, which can lead to tunneling. Keep the candle away from air vents, windows, or drafts. If you notice the flame flickering, or it appears to be tunneling, move the candle to a place with less air movement.

Do put your candle on a heat-resistant surface.

This one may seem obvious, but it bears repeating. Be sure your candle is on a steady, heat-resistant surface before you light it. Otherwise, you may damage your furniture. (And of course, keep your candle away from flammable objects—and away from any kids or pets who might knock it over.)