We meet as a team with coaches present 3-4 times a week over the summer, starting the week after track ends. Our school spans two towns so we usually try to do at least one practice in each town, and once a week in the morning. That makes it easier for those who have summer jobs or can't drive to get to some of the practices. We also are able to get a bus to take us to a park about 30 minutes away a few times a month. It has more challenging terrain and is a great team bonding time.
Give out a training plan with at least 3 levels based on experience/fitness - we make the "run on your own" days easy 3-6 miles and any "workouts" are done with the team.
You can read every book and have big goals but you need to know who you have and their level of fitness or it will be frustrating for everyone. Respect and listen to your athletes. Know the "Why?" to each workout and base it on reality.
Get to know what they thought worked well, previous amount of miles, strength training, core, etc., what the jr high program is like.
It might take some time to develop culture and success, especially if it had been lacking in the past or it might happen right away given the right combination of attitudes and talent. Either way, have fun and good luck