It's also important to make sure that the trench coat you choose is of good quality. Getting a cheap coat not only leaves you freezing in the cold, it also looks, well, cheap!
New York and Company has the most adorable trench coat ever. (Nice plug for my other place of employment! haha). It comes in black and tan (tan is the better choice, as it goes with nearly every outfit). Their Ruffle Trim Classic Trench has the cutest ruffle hem along the bottom. It's fabulous because the ruffle adds a unique detail, but the overall look of the trench remains classic.
You can buy one of these adorable coats for under $90, which is really a steal. This is definitely a purchase that will last for years!