Use a brick chisel to break away any cracked or loose mortar in areas that have been previously patched.
Sweep any debris off the patio surface. Thoroughly clean the concrete with a high-strength pressure washer.
Mix up a patching compound per the manufacturer's instructions and fill any holes or cracks. The mixture should set up about a quarter-inch. Allow the repaired areas to harden.
Section off your patio into work areas that are no larger than 144 square feet. Use control joints and expansion joints to help you define the work areas. Mask any areas that will not be covered with resurfacer.
Mix resurfacer powder and water (following manufacturer's instructions) in a 5-gallon bucket with a drill and paddle mixer. Saturate the patio surface with water, but remove any areas of standing water.
Pour the resurfacing compound onto the patio and spread with a long-handled squeegee. The mixture should be 1/16 to 1/8 of an inch thick. Use a wallpaper brush (available at hardware stores) to cover corners or edges.
Within five minutes of applying the resurfacer (the surface should be somewhat firm but still malleable), drag a push broom or a masonry brush over the work area. Pull the broom toward you, making sure that each stroke goes the full distance of the work area and all the broom strokes go in the same direction.
According to the resurfacer package instructions, wait at least six hours before walking on the patio.