I use "come on" as a lets go, walk. "Get back here" when Bear,my lab mix, starts moving faster than I desire and hadmade progress in said move. "Hey" or a grunt noise to stop a move caught more quickly. The nice thing on the trail, or walking in our small Kansas community, Bear keeps an eye on me and if I get to far behind he comes back to find me; he also comes if he gets behind more than 10 feet(yeah I need to keep a better eye on him when he finds a smell). The funny thing is he does it less on trail than walking our daily exersice route.