Many classrooms use the phrase "Three before me" to set the expectations that students will ask 3 other students before raising their hand to ask a teacher. This can be helpful for reducing the number of administrative questions that you have to answer and can facilitate students working together. Before helping a student who raises their hand, ask them which of their peers they had already asked.
Example: "Ask three before me!"
See this and related tips as a Tip Sheet: http://csteachingtips.org/tips-for-lab-rules