A guitar strap can be highly personal choice. Straps are available in many materials and designs - common favourites being black leather and tweed. A wide, padded leather strap can help distribute the weight of a heavy guitar such as a Les Paul and avoid the feeling that the strap is cutting into your shoulder. Some straps are continuously adjustable in length while others are adjusted by adjusting the placement of a buckle.
Strap-locking devices are a very cheap and effective way of securing your instrument when it's in use. Many different methods are currently available, and most of them take mere minutes to install.