How can you tell when a product is really, really popular? When the downtown Macy's, Nordstrom, and Sephora are all completely sold out of it. Nars Velvet Matte Lip Pencil in train bleu (now back in stock downtown) is perhaps the perfect deep aubergine for autumn. The lip pencil—really more of a lip crayon—has a purpled burgundy hue with cool undertones. Think wine and falling leaves and dark plums. This shade is sultry. 

We love the Nars pencil because it's richly pigmented, easy to apply, and has a non-drying matte finish. But we have to admit that it takes some serious confidence to wear fall's go-to lip shade. To help you courageously go over to the dark side, here are our tips on how to best rock November's alluring hue:

-Exfoliate. Dark lipstick accumulates on dry, flaky spots giving you that patchy, just-drank-some-red-wine look. Starting with a smooth surface is essential. Pick up a lip exfoliant like Bliss Fabulips sugar scrub or make your own, and rub into lips in small circles. Follow up with a hydrating lip balm to lock in moisture.

-To fill in fine lines and prevent feathering, use a lipstick primer—we love the Line and Define primer from Bite Beauty. Primers also increase staying power and keep lips nourished.

-Choose matte finishes rather than shiny ones. Glossy dark shades tend to bleed and look gloppy.

-The Nars stick is great because it's a lip liner and lipstick in one. If you're using a traditional stick, be sure to line lips in a matching shade and carefully apply lipstick using a lip brush—mistakes and imperfections are more obvious when wearing deep colors.

-Tone down the rest of your makeup; it's too easy to cross the line into Twilight-face. Only wear a subtle blush to keep from looking washed out, mascara, and a bit of eyeliner. Pulling hair into a sleek pony or bun also keeps it clean and chic.

Grab the Nars Velvet Matte lip pencil at downtown's Macy's, Nordstrom, or Sephora for $24 before another shade shortage hits stores.