Probably the most important thing you can do to preserve your asphalt. All asphalt is going to crack no matter what you do or who you hire. There is no way around it. The big thing is water, cracks will allow water to penetrate your asphalt. Once inside it will start to eat away at your asphalt from the inside out and eventually your base. Even if you have great drainage water will still run into the cracks. Asphalt will contract and expand with the temperature getting larger during the winter, shrinking during the summer. The best method of crack sealing that will allow for movement is to router (cut cracks 3/4" by 3/4" or 1" by 1/2" depending on cracks size) cracks to create a reservoir for the sealant to sit in. The rubberized sealant (very flexible) will be applied hot (350* degrees) into the reservoir and be banded on both sides of the routered crack. This way allows for more rubber and will be flexible when the crack expands and contracts. Routered cracks will last 3 times longer. The other way is to leave cracks as is (no router) and fill to just below flush. All cracks are intentionally left low for snow removal.