Pavement Thickness: The optimum thickness for a long lasting, trouble free application is 4 inches (2.5" base and 1.5" top). Less may result in earlier repairs/replacement. Accept nothing less than 3" as it is likely to fail in less than 5 years.
Grade (slope), drainage and soil conditions: There needs to be adequate drainage to keep water from accumulating under the pavement. Freeze/thaw of the water will break up the pavement.
Patching and compacting holes and other trouble spots in existing pavement: In existing driveways, poor drainage or gas spills can cause bad spots which can cause failture of resurfaces if not repaired beforehand.
Sub-grade preparation (including chemical spraying to prevent weed growth): There needs to be adequate stone (6-8") under the pavement to provide a firm base. This helps prevent the pavement from moving and also assists in drainage. Less may jeopardize the length of life of the pavement. Weed/seed under the pavement may result in growth later through the pavement and cracking/holes.
Compacting the pavement to specified thickness:
Compaction of the pavement (and the sub-base underneath) increases the strength the pavement and improves the smoothness and general appearance. A small roller will not generate enough compaction. Returning the yard to its pre-construction condition. If a yard is not restored so that soil/grass rises to just below the level of the pavement, water can more easily get under the pavement, plus the edges of the pavement may crack and fall away because of lack of support.
Warranties: Ask about any warranties. They should be in writing, signed, and of at least one year in duration, covering materials and workmanship. This is the standard in the industry.