Whenever you're doing construction work, you need the proper safety gear. Safety goggles are necessary to protect your eyes, and ear plugs are required to protect your ears from the loud noise of the power tools.
A tape measure is required to measure the exact lengths of the wall studs you'll need for the top and bottom stud plates and vertical wall studs. A plumb bob is needed to verify the positions of the top and bottom stud plates are plumb. A wall that is out of plumb will be crooked. Once the wall is up but before it is nailed in place, a level should be used to further verify the wall is plumb.
Either a power circular saw or miter saw is required to cut the studs to length, and each tool has its advantages. A circular saw is more portable, but an extremely steady hand is required to get a 90-degree cut. The miter saw, because of its large base, is not portable, but the blade arm can be locked in place for a 90-degree cut to guarantee the stud is cut properly.
A hammer can be used to drive nails into the studs to form joints. If you are framing multiple walls, it will be quicker and easier to use a framing nailer. A framing nailer is a gun that uses compressed air to drive the nails into the studs when you pull the trigger on the gun. While framing nailers can be expensive, they can be rented from most home improvement stores.