Be respectful to each other and the coach.
Other than that, as a coach, you have to remember this is play time for the kiddos. You want them to learn soccer skills, but forcing them to do this or that will only backfire. As a coach, you prepare their environment, demonstrate the desired activity, and then invite them to explore it to their hearts content. They may refuse the invitation. That's okay. Maybe they just want to watch. Maybe they want to do something completely different. This is where you invite their parent to take over while you pay attention to the rest of the team.
I once tried to make my daughter run her fastest (she was 9 or 10 years old). For whatever reason, she refused to do anything more than jog quickly. The conflict took the fun out of the game and it definitely didn't make her run any faster. Now, several years later, I think (hope) I would handle it better. I wish I'd asked, "Why?". Not a frustrated plea, but a genuine desire to understand her motivations. Maybe I would have gotten a reasonable answer, or maybe not. Still with some honest inquiry, I would have actually learned more about my daughter and made things better for both of us. By expecting her to immediately obey my command to run faster, it only frustrated both of us. Do your best to prepare the environment and try to see things from their point of view when it isn't working. When it is working, let them play.