An existing plains, desert or village will provide a place that you can build your structures with the least difficulty. Rugged mountains and natural tunnels can provide suitable funnel points to build walls and doors for security. These will make it more difficult for mobs to attack your team, or vandalize your structures.
If you would like an alternate mode of transportation for the people who live in your city, include a Minecart path in the middle of the roads. This makes it so that people can walk or ride the Minecarts to where they need to go.
Use height to your advantage. Put multiple rooms of the same size on top of each other to make a home that can house more than one person while using the least amount of space. Make sure your home includes the basic structures for a person to live comfortably. A bed, chest, crafting table, and furnace are needed for a person to survive in Minecraft. Start with the basic skeleton of the buildings, and add details later. For example, if you’re building a hotel, you might want to just create the walls (don’t fill them in yet) and place blocks where you want your different levels to be.
If you want to make your school even more realistic, you can build some of the common rooms found in a school such as a cafeteria, gym, or music room.