Robots determine how much hydrogen is in the lunar crust, and where it's located. (Note: this step is crucial. If hydrogen is not plentiful and easy to mine from the lunar crust, then the plan to return to the moon is not viable.) One such robot has been proposed by NASA scientists. The Resource Prospector would deploy a rover that can search for hydrogen, drill into the lunar regolith, and heat samples to see what's inside. If the mission gets funded, it'll be the first mining expedition on another world.
Develop reusable spacecraft to get humans to and from the moon
Land humans at the equator, probably using SpaceX's Falcon Heavy rocket, which is still in development but estimated to cost $1700 per kilogram
Develop technologies to mine the lunar ice
Develop reusable lunar lander to carry equipment back and forth from lunar orbit to lunar surface
Send humans to the lunar poles
Select a site for mining
Use lunar lander to deliver Bigelow Aerospace inflatable space habitats to lunar surface for human occupation. The habitat modules could be located in a lava tube for protection against radiation.
Deliver a crew of four astronauts to live on the surface and assist in repair of the largely autonomous mining equipment.
Begin mining for hydrogen
Lunar lander delivers 200 metric tons of propellant per year to a depot at Lagrange point L2--a stationary spot in lunar orbit on the far side of the Moon