From Women's Health:

 Whether you’ve just run out of your favorite  leave-in conditioner or feeling like your strands need more TLC, you  might want to take a look in your kitchen before heading to the  drugstore to restock. From dryness, to frizz, to flakes, and more, we’ve  asked the pros for their best DIY hair mask recipes to target every  kind of hair concern. Once you've decided which  mask is best for your strands (keep scrolling to make your pick),  you'll just want to make sure you follow these pro application tips to  get the most out of your recipe. “I definitely think the way to go when  applying DIY masks is to apply them to dry or damp hair, then shampoo  and condition as normal—this gives you a little buffer if you  accidentally over apply the mask,” says Judy McGuinness, a stylist at mizu Louis Licari.  “There’s nothing worse than putting a concoction on your hair only to  find out it won’t rinse out after a few shampoos!” Make sure to apply  the majority of the mask to the mid lengths and ends of the hair (unless  it’s a scalp detox mask), as that’s where the hair is the oldest and  most damaged or dry. With any hair mask, Mahshid Baghaei, a colorist at mizu Louis Licari,  recommends a 20 minute processing time to make sure it penetrates the  cuticles and seeps into the scalp, if trying out a scalp mask. “Adding a  shower cap will also help speed up the process,” says Baghaei. “After  the processing time, shampoo the hair lightly and condition as usual,  unless you have a heavy conditioning treatment in your hair—then just  rinse the hair after shampooing.” Another thing to remember: “Always be  extra careful when rinsing masks out in the shower,” Paul, celebrity  stylist and owner of Cucinello Studio NYC. “Most have a lot of oils and emollients in them, so they create a super slippery situation on the shower floor."  (Read more.)