Preparation:

Completely inspect all the rigging on the mast with detail paid to the swaging of the stay wires into the fittings. Over time some of the strands of wire can fail at the end of the compression fitting. If any strands are broken, the stay should be replaced to eliminate any stay failure under sailing load.
Check all riveted fittings, spreader connections, main and jib halyard pulleys, and wire/rope halyards for being in good condition. When in doubt repair or replace.
Clean the mast including the mainsail slot to keep the sail clean. Install a wind indicator on top of the mast. This is very important whether a day sailor or racer to know the wind direction particularly for off- wind sailing.
Have a mast support mounted on the stern of the boat to support the mast and allow the pin at the foot of the mast to be inserted in the mast support fitting on the cabin top. Have someone help you set the mast in the rear support. The rear support needs to be high enough to make sure the mast clears the cabin top when in the horizontal position.
Connect the 4 side stays to the chainplates and make sure they are not twisted. The lower side stays connect in the front hole of the chainplate. The upper stays connect to the rear hole in the chainplate.
Connect at least a 20' line on the headstay above the connection point for someone to assist when putting the mast up. Try to have the boat /trailer facing into the wind.
Block the wheels and the back of the trailer so it will not tip up if you get too far to the stern in the boat.

Mast Up:

One person is needed to pull the headstay attached line as you lift the mast while standing in the cockpit. Push the mast up as fast as possible to minimize the chance of the mast swaying side to side.
With the mast up, confirm that the 4 sidestays/turnbuckles are aligned. Pull on the headstay line and connect the headstay to the front most hole in the bow connection fitting. The backstay can be connected after the Rigging Setup is completed.

Rigging Setup:

Check that the lower side stays are not under any tension and the upper side stays have some tension on them. Check that the spreaders are horizontal.
Attach a 30' or longer measuring tape to the main halyard shackle and pull it all the way to the top of the mast and cleat the halyard. Pull the tape to one of the side chainplates and note the measurement. Go to the opposite side of the boat and make the same measurement. Adjust the upper sidestay turnbuckles as necessary to end up with the measurements the same on both sides of the boat. The mast is now centered side to side on the boat.
Pull the tape to the center of the top outside edge of the transom and note the measurement. Most boats tuned for racing have a measurement of about 27'10" to 28'0" to give a good balanced helm while sailing the boat. If this dimension varies much from the above measurement range, adjust the headstay to get within the desired measurement range. (The more rake in the mast will give more weather helm when sailing upwind)
The upper sidestays are then tightened equally to keep the mast centered side-to-side. A Loos gage can be used to get to a sidestay tension of 200-250 pounds. There should be a mast support (2x4 or angled pipe) directly under the mast in the cabin if you want to apply the 250-pound tension to prevent the cabin top from flexing as well as keeping the rig stiff.