It's difficult to overstate the importance of warming up for exercise. Jump rope is often used as a warm up for other forms of exercise and is a great way to get blood flowing to all the different muscles you'll likely be engaging. However, if jump rope is your exercise activity for the day, it is wise to do some dynamic stretching prior to getting started.
Why is it that so many people can get 1 …. 2 …. maybe 3 double unders in a row, but struggle to string together a whole set? It is such a joy to see athletes try this simple experimentation and finally get it!