First for a warm up I would put people with the same football skill playing vs each other also keeping in mind how they can dribble and how good they are in football they will be playing in the small goals without a goalie this warm up will be good because people with closer skills in football may play better. Then I would try to but people with various skills together so they have balanced teams I would also try to put them in the position they are best so that way people will play together very well or also we could keep the warmup teams and they each play for 3 mins that could help because people with close skills in football may play better together.