I'm not sure if it's tips or advice, but in my experience middle school coaches are not the cream of the crop of the coaches in the district. If they were good coaches, they'd probably be at the high school. There will likely be a ton of kids out there, so the kids don't get the attention that most of them need. Basically, all the boys play in 7th grade and then it slowly dwindles in 8th and 9th. I've had boys play for middle school and youth football leagues in middle school. When we lived in Texas, they had middle school ball. My 17 year old (going into his senior year) played middle school in 7th grade. Then when we moved up to Missouri, they didn't have middle school ball, so he played youth league. He was fortunate that the youth coach that year was a former high school varsity head coach and had taken a position as a principal, so no high school coaching anymore. That was the year that my son turned it on. Best coaching he ever had.
In short, it depends on the coaching staff at the middle school. Good luck and I hope he enjoys it.