The darker the sky, the better. Obviously, faint objects are easier to see in a dark sky. But if there's a lot of stray light around, you can improve the situation by shielding your eyes with your hand or the brim of a hat. In the cold weather, the hood of a parka can do double duty. A rubber eyecup attached to the eyepiece is a big help.
Some observers cover their heads with a dark cloth to cut out ambient light.
However, another problem occurs when the sky is really dark. Then there are so many stars visible that it sometimes becomes difficult to starhop until you get over the initial confusion. A good star atlas is a must. There should be a law that anyone who buys a first telescope must get a good star atlas. Forget about the little pocketbook-sized field guides to astronomy.