In addition to your basic utility knife, you'll need some special tools for cutting drywall sheets.
For making square cuts, use a drywall T-square. Set your sheets of drywall upright with the smooth side out. Set the T-square on the top edge and line it up with your measurement. Run a utility knife along the side of the "T" to score your cut. Snap the sheet back to break the sheet along the cut. Then cut the paper back with a utility knife.
For making cuts around obstacles you can use a drywall saw. Just use a back-and-forth motion like you would for any hand saw.
Cutting your sheets slightly too big is better than too small. You can always shave the ends off with a rasp.
For cutting around electrical boxes use a keyhole saw. Just punch the tip through the drywall and cut along each side. You can also use a power jig saw for these cuts.
For round cuts, like around light fixture boxes, use a circle cutter. Find the center of your circle and punch in the center marker. Adjust the arm to the radius of your circle and use it to score the perimeter of the circle. Do the same on the other side of the sheet. Tap out the cut out with a hammer. You can also use a compass to draw the circles, and a keyhole saw to cut them.
There's also a power tool professionals use that's designed specifically for cutting out holes for electrical boxes and fixtures. It's like a drywall router, and they use it to cut the holes after the sheets of drywall are up. This is a lot faster then cutting them all by hand.
If you do end up renting one of these power routers be careful so you don't strip the electrical wiring inside.
Drywall Lifts and Jacks
Getting drywall up to the ceiling can be tough. You may have seen professionals or do-it-yourselfers hold it up to the ceiling with their heads. This works, but does require some coordination and can be kind of awkward.
You can rent a rig called a drywall lift. You load a sheet on it, then crank it up to the ceiling. It holds the sheet in place while you nail or screw it to the joists.
You can also use a couple of drywall jacks to hold sheets of drywall up to the ceiling. You can construct these out of 2x4's. Make the overall height just an inch or two taller than the height from the floor to the underside of the joists or trusses.
Using 4-foot sheets on a standard 8-foot wall usually leaves you with about a 1/2" gap left. You want to leave this on the bottom so it gets covered up with baseboard. To help hold the bottom sheet up snug to the top one use a drywall lifter. You just step on one side of it and it lifts the sheet up. You can also use a pry bar for this.
For nailing up sheets of drywall, a drywall hammer is a must. It has a convex head that creates a little dimple around the nail head without breaking the paper on the surface of the drywall. This will allow you to cover the nail head with drywall mud and get a perfectly smooth surface.
Using drywall screws can go a lot faster, if you have the right tool. You want to use a special electric drywall screw gun that lets you adjust it to sink the screws a little below the surface, again, so you don't break the paper. With a regular screw gun you don't have this control.
The "art" of taping comes from using different sized taping knives to get a smooth, tapered joint.
For the first "tape coat" you'll need a taping knife that's 5" or 6" wide. With each of the next two coats you'll want to cover an inch or two farther in each direction so you'll probably need an 8" to 10" knife and a 12" to 14" knife.
Use a mud pan to hold the mud as you tape the joints.
For sanding the joints, use either a pole sander for dry sanding, or a wet sanding pad.
For applying texture to ceilings you'll want to rent a sprayer specifically designed for this job.