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We're all guilty of committing a food storage crime or two.  Have you eaten those leftovers that even though old  still smelled OK?  Have you made soup and let it cool on the counter for a couple of hours?

In the April issue of Real Simple, editors consulted with U.S. Department of Agriculture, food scientists, food manufacturers and other experts  to establish an all-encompassing guide to food storage.  We spoke with the magazine's senior food editor Lygeia Grace to get her top tips on how to keep food tasting fresh and avoid letting it go to waste.

To see the full comprehensive list from Real Simple, click here.

Here's  the five worst food storage mistakes:

1.  If it doesn't smell bad, it won't kill me. 

"Leftovers should last four  days tops," says Grace.  While people might think it's OK to eat food past that time, "it's not safe,"  says Grace. If the dish contains fish, make sure to eat it within a day or two.

2.  That hot plate of food on the counter sat there for hours.

"The longer food sits out, the greater the chances that bacteria is going to grow.  If you're going to save food for leftovers, put it in the refrigerator.  Put large portions in smaller containers.  Letting things sit out can be dangerous," says Grace.  Rice can harbor a dangerous bacteria called bacillus cereus, which occurs when it sits at room temperature for several hours.

3. The frozen chicken sat on the counter to thaw.

We've all experienced that panic of having forgotten to defrost dinner.  "The safest way to thaw things is overnight in the refrigerator," says Grace. "The second method is if you have it in an airtight resealable bag in a bowl of cold water and change the water periodically when the water gets warm."

Avoid defrosting the food item in warm water, which will cook your food rather than defrost it.

4.  You're not sure if that unlabeled frozen steak is two months old or a year old.

The only way to tell if your food is still fresh is if you know how long it's been living in your freezer. "Over time food will take on the flavor of other things in the freezer," says Grace.

Grace recommends properly packing and labeling all frozen foods.  "The trick to freezing a lot of meats is how you do it.  You want to protect it from freezer burn.  Short term, slip the packaging into a resealable freezer bag and wrap each piece individually," says Grace.  She recommends buying containers that are labeled "Freezer-safe."

5.  Dented cans sit idly in the cabinet.

Grace recommends throwing away "anything that is dented or leaking.  Botulism is more of an issue for self-canning, but dented cans have a higher risk of botulism."

Even if they're not dented, acidic canned foods such as tomatoes or fruit can lose flavor after one to two years.  Other canned foods can last up to five years but, Grace  insists, "When in doubt, toss it."