With the winter months upon us, the cold has an irritating tendency to suck all of the hydration out of our locks — leaving us with lackluster, dry hair. The solution to quickly adding a dose of TLC to your strands? Slapping on a good ol' deep conditioner.Think of deep conditioners as a way of pressing the reset button on your hair. They help to restore strength and replenish moisture from normal, everyday stressors, leaving you with what will seem like a brand-spankin'-new — and healthy — mane.But while hair masks are a widely known product, how to properly use them is still a topic of debate. Is leaving on overnight frowned upon? Should you apply before or after shampooing? And, of course, all hair masks aren't created equal. So which one should you actually be using?For guidance, we consulted celebrity hairstylists Chuck Amos (he works with Solange Knowles, Jordin Sparks, and Tracee Ellis Ross) and Derek Yuen (clients include Jaime King, Joanna Newsom, and Constance Wu) to get the lowdown on all of these pressing questions and more. Click through for their pro advice, then feel free to add "taking better care of your mane" to your 2016 resolution list.