Forming groups
There are many different ways of forming groups. Are you going to let students choose who they work with, or are you going to stipulate who works with each other? Do you want your students to work in the same groups throughout the semester, or work with different students each time? If you decide on group formation before the tutorial, what do you do if students are absent and you have some very small groups? There are no right or wrong answers here, but it is important that you spend time thinking about this as you design your tutorials.
One very quick way of forming groups is to put students together depending on where they are sitting. Another successful method is to decide how many groups you need (based on the tutorial design, of the number of students present) and then go around the room allocating the first student to group 1, the second to group 2, etc. until all students are allocated to a group.