"If you're worried about panty lines showing through leggings or tight jeans, don't go commando," advises Cornwell. Instead, choose a seamless low-rise panty, like the Commando Cotton Low Rise Bikini.

Low-rise panties are also great for preventing your underwear from riding up above the waistline -- you know, that awful thing that happens when you inevitably end up flashing everyone in the room each time you bend over or reach across the table?

Hernandez's favorite low-rise options include the Cosabella Trenta Lowrider Thong and the Hanky Panky Signature Lace Low Rise Thong.

Likely the most common underwear problem, panty lines happen to the best of us. "Panties trimmed in elastic create the worst panty line," says Hernandez, "They're the worst bulge offenders too."

Bras can create their own versions of panty lines. Celebrity stylist Samantha Brown (of OkMyOutfit) says these obvious lines are caused by wearing bras that are "lacey, embellished or with heavy seaming" under thin and lightweight fabrics.

Seamless underwear lies flat against the skin, and is typically made from soft, stretchy fabric, sometimes trimmed with lace. Seamless panties range from cheeky cuts to full coverage. Hernandez's favorite seamless picks include Calvin Klein's Invisibles Hipster and Commando's Better Than Nothing classic bikinis, girl shorts and thongs. "With all the seamless options out there, panties with elastic should be extinct," she says.

Brown adds that the Spanx Oh My Posh! High-Waisted Thong is a great seamless option if "you're looking for tummy control but want to avoid full coverage."

For reducing bra lines under light tops, Brown recommends the Spanx Bra-llelujah Soft Touch Underwire Bra. "It's seamless with a smooth back and thick straps that won't dig in," she says. "It isn't sexy but it does the trick!"

It's one thing to find the right undergarments for your everyday clothes. But sometimes, an occasion comes up where you have to wear a formal dress or gown, and suddenly, having the perfect hourglass shape feels very important. We don't all have a celebrity figure; so having to break out a fancy, floor-length dress can feel overwhelming.

During times like these, everyday undergarments simply won't do. Luckily, the technology for creating a gorgeous hourglass shape exists, and you don't even have to sell your soul to get it.

For creating a slim hourglass shape, we look to our Victorian ancestors for guidance. "Don't be afraid of using a corset," says Cornwell, "I say 'corset,' and you immediately think of Rose from 'Titanic' getting yanked until she can barely breathe." But modern corsets aren't quite like that.

Cornwell says there are so many different kinds of corsets on the market today that you don't have to be scared to try one out (the Spanx Boostie-Yay! Comfy Corset is both flattering and comfortable).

"They really do lift the chest and shape the upper body, while also bringing in the waist and smoothing out the tummy," Cornwell says. "You definitely don't want to wear anything skimpy with a corset, because it will show through, but for ball gown type of look -- a wedding or special event -- it can work perfectly."