Compaction is one of the keys. A lot depends on the composition of the original material. A good 4" of Class II Base material on top of the original grade is always helpful. "Fine" mixtures from the asphalt plant have a shorter lifespan than than "Medium" mixes.
no one around here puts 4'' down , always 2''...had mine done twice , but they couldn't use a big heavy roller to compact it with , due to running under a carport/portico .
reseal time coming up...