I've found that generally the inverse of your focal length is a good yardstick for setting your shutter speed to begin with. That is assuming you will be filling the frame with your subject.
Eg. if you have a 300mm lens, start at around 1/250s and work down. If AF cannot cope with the rapidly changing subject, then prefocus before tracking and firing.
Panning is a physical process that requires you to swing your body through an arc while tracking the subject steadily in the viewfinder.
After knowing the settings, just remains to practice, and keep practicing.