Listed at the bottom are a few tools that will make installation a lot easier. Drywall the walls and soffits first. The ceilings are easier to keep level if you have a ceiling laser but one is not necessary. Pop BLUE chalk lines for the TOP of the wall angle. Blue chalk will wipe off if you get in on the wall, red won't. Install the wall angle before doing anything else. The next step is to find the center of your room both ways. Depending on the size of the tile, put pencil marks every two or four feet. When you get to the wall measure how much you have left to the wall to determine what size border you will have. Pull a string or jetline from one wall to the opposite wall with the string being the same distance off the side wall at each end. Do this for the other two walls too. This string will be the center of your ceiling mains. Use the clamps shown below to hold the line in place. Next step is to install mains. Run the mains the opposite direction of your joist. Once you determine what direction your mains will run, measure from the string to the wall to determine where the main needs to be cut. Once you get the measurement, measure from one of the notches in the main where the tees snap in and cut the main whatever measurement you need. Do this to two mains. You will need your grid hanging wires installed to continue. These wires should be no more than four feet apart. Install the first main then measure four feet along the wall to where you will install the second main. Be sure the notches for the tees are centered on the string. You will need to be sure the first main is centered on the string at least for the first several feet. Once you have the two mains installed put a couple four foot tees in connecting the mains with the first tee being centered on the other string line. These tees should be two foot apart. Now you can check to see if the ceiling is square. Measure the rectangle you just created diagonally in both directions to see if it is square. If I remember correctly, the measurement should be about 52 1/4 inches. If you have the same measurement both directions pop rivet the first two mains to the wall angle. You will need to cut the tees to fit to the wall that is parallel to the mains and clamp or pop rivet them in place. After you do this you can continue installing mains and tees. Pop rivet one end of each main as you install them. Do not pop rivet the other end. This will allow for expansion and contraction. If you can send me the measurements of the room and your email address I can make a drawing showing how to lay the ceiling out in the room.
James
BTW, I've been doing drywall and ceilings for 30 or so years.
Clamps like these:
http://www.ebay.com/itm/30x-2-inch-M...item19ee4afe70
Wire cutters
Pop rivet gun and pop rivets
Jetline or some other small string or thread. Wherever you but the grid from will have this.
Tape measure
Snips to cut the grid