2. Approach quiet students
After students sit down and don't raise their hand, if you ask them if they are doing OK, often they will say “No”. The lesson is "Some students are shy to ask for help, especially in the beginning, and especially if the tutors have just arrived and don't yet seem settled in." However, their and your time is valuable, so be sure to help put that time to best use by proactively asking them if they need assistance as soon as they arrive.
Conversely, some people really do need “settling in" time, after they arrive but before they are ready to learn. Don't be frustrated with people who decline help immediately upon arrival, but then seem to change their mind without having done any intervening study. They have just completed "settling in" and are now ready to learn. Be sure to return to them!