Just make sure your top isn't too fitted—it should effortlessly drape a few inches beneath the top layer, not awkwardly scrunch up. Tucking, as well, in an option, but only if your jacket skims right below the waist line of your pants.
So long as it peeks out between one and six inches, a trench shows off your bottom layer without overwhelming the look. You can sometimes get away with doing a shorter hemline, too, but only if you leave your coat open the entire time—when none of the actual outfit shows, it looks like you're on a booty call.
Double-Breasted Trench Coat, $635, A.P.C., barneys.com; Button Back Dress in Navy Abstract Floral, $365, No.6, no6store.com
The Outerwear: Long Trench Coats
Pairing #2: Any Pants
The main thing to avoid with full length trenches in looking naked underneath, so something that covers your legs is a safe bet.
If you've been scared of the culotte trend since reared it's questionable head last February, here's how to get it right: add a strong, structured biker jacket and substantial heels to anchor all that voluminous fabric.