Strap. There are a variety ways to approach this. You can make a trip to the local fabric store and purchase a strip of cloth, which can then be folded over itself multiple times to make it strong. Other people can cannibalize old backpacks, luggage, belts, purses, whatever you might be inclined to use. You can be as stylish or as practical, as comfortable or as minimalistic as you desire. You can even just create a fabric sheath to fit over another, more durable strap for greater comfort while still being strong. The variations are endless.
The length is also up the personal preference; while the traditional way to “wear" a camera is around the neck, some people dislike how conspicuous this is (a “nerd necklace"), preferring it around the shoulder so it sits at the waist. These same guidelines also apply to making wrist bands.
Clips, another thing with considerable variation. Most people prefer the strap to be clipped to the traditional holds on either side of the camera, while other people prefer a direct connection to the camera mount. If you prefer the former, any clip will do, as long as it fits and is strong. Keyrings, carabiners, snap swivels... all are possibilities.
Other supplies vary according to your choice of strap and clip, but nothing out of the ordinary is necessary.