Step 1: Supplies
Paracord can be found at local Army/Navy stores or from various online sources: Supply Captain, Lighthound, Cool Glow Stuff!, ebay, etc...
The actual amount of paracord that will be used depends on your wrist size. My wrist is about 8.5 inches and I actually used around 8 or 9 feet after finishing the bracelet/watchband. So using 10 feet is a safe estimate for most folks, since having too much cord is better than coming up short when making your project.
*If making a watchband, the watch needs to have about 5/8" space between the lugs(where the watch pins go) so that 5 strands of paracord will fit.