First and most important (for me) is that you have loose leash walking mastered. Also some good impulse control when your dog sees little critters running across the road in front of you. You will also need to really learn your dog's potty habits so you know when he needs to stop to poop/pee versus he just caught an interesting scent.
After that, what Lies and Emoore said is pretty much it. You just start running and make sure you don't overdo it.
Niko: American Showline GSD 5 years old
Rosa: American Muppet Dog (GSD/Border Collie mix) 5 years old