Install rigid foam over the existing clapboard siding. Use galvanized nails to fasten the foam insulation.
Use a level and a chalk line to snap a guide line around the base of the house. Consult the siding manufacturer's instructions regarding how far off the ground this guide line should fall.
Follow the chalk guide lines and nail a starter strip along the base of the house. A starter strip is a folded strip of aluminum on which the first course of vinyl siding will be secured. Leave 1/4 inch between each piece of starter strip.
Install the inside and outside corner pieces. Nail these pieces through the prefabricated nail slots. Don't drive the nails down tight; leave 1/16 to 1/32 inch of the nail shank above the surface of all vinyl pieces to accommodate expansion.
Install the J-channel along the edges of all doors and windows, and along any sloped eaves. Fasten undersill trim under the windows and along any horizontal eaves.
Install the siding panels. Start from the base, along the starter strip, and work your way up. Overlap the panels by about 1 inch, and stagger the joints between siding courses by 4 feet. Leave a 1/4-inch gap between the end of the siding panels and the end of the J-channels. Check your level every 5 or 6 siding courses as you work your way up, and make minor adjustments accordingly.
Around windows, doors, and fixtures, mark the excess vinyl material that will need to be removed. Use tin snips to cut the panels vertically, and a utility knife to slice off the excess vinyl. Use the snap lock tool to create dimples every 16 inches in the cut edge of the vinyl siding. These dimples will allow the cut edge to snap into the undersill trim.
At the top of the house, with horizontal eaves, use the snap lock tool to create dimples in the cut edge of the material; then snap the cut edge into the undersill trim. On sloped eaves, cut the siding panels using your utility knife and tin snips, and fit the cut panels into the J-channel.