THE SECRET METHOD
Whether or not you are working alone, it is advisable to start the nails in your plywood before attempting to carry it up a ladder. Next, make certain you have a hammer riding in one of your belt loops. With your trusty hammer at your side, drop to one knee. Place your right cheek against the board. Slide your fingers under the bottom edge of the plywood. Now slowly lift, preferably with your legs, but more likely with your back and arms. To keep the board from wobbling, (this is the crucial, secret part that I personally developed) apply pressure by filling your cheek with air. Slide the board up the ladder, then the wall. When the board is lined up and flush with the 2X4 studs, add the weight of your shoulder into the equation to free your right hand. Fumble for your hammer while the board slips two inches. Lift again...slip...lift again. If the board starts to flip away from the wall, do not panic. Head butt the board to keep it in place (this is another of my innovations).
When you believe that the board is properly aligned, take a broad swing at the starter nail...don't worry about hammer marks. With any good luck, Grandma will not show up until after you have gotten the siding in place over the sheathing. Beat the nail until it is firmly planted in the 2X4 stud. Producing more nails from your handy tool belt, secure said sheathing in place.
Repeat this secret method until all walls are covered.
I am sure you can see how this method simplifies the whole sheathing process. Don't forget, it is patented (at least it is copyrighted), so please send 38 cents for every incident of usage. A cashiers check or cash will do nicely.