DO NOT get rooked into going with the fly by nighters going around doing it that are coming out of the woodwork right now. If you are going to get it done, get it done by a reputable company that does it year after year and has a longevity record of being in business. The fly by nighters use a water based product and when they buy it, they cut it some more to stretch it out. A legitimate company will not be cutting their product.
If you do it yourself, don't cheap out on it. You will find there are two products. One will be water based or coal tar based and the other asphalt based sealer. The coal tar is a better sealer to some, to others they may argue the other is better. You will also find that some will have sand in them and others won't. The sand based products will give you some gription, whereas the others may leave the surface real slick, and especially slick when wet. So if there will be elderly people walking on the drive, you may want to go with the type that has a traction additive.
My neighbor lady just had hers sealed the other day. She hasn't had it done in years, so she sent the guy over to talk to me about what was to be done. I spoke with him for a while and she came over to confirm what was being said. I specifically asked him about filling the cracks and he said he was going to do it, then seal it. I had to go get gas for the mower and when I came back, they were almost done. He didn't do what he said he was going to do, and he didn't
use the product he said he was going to use. I went over to see what sort of job he did. ****** for sure. He didn't edge the drive, they swept it off with a broom and a little leaf blower, then sprayed the sealer. No cracks were filled. When he started to be questioned by me, he got on the defensive real quick and wanted her to pay full price and he would be back next week to give it another coat to make sure the cracks were filled. But he told me that he had to pay for the sealer, that's why he needed the money now. I asked him then
how was he going to coat it next week for free. No answer. He finally settled for $50, which wasn't bad for what it was, but by far not a real decent job. He's flashing this pamphlet which was not the product he was using. And when I asked him how long before you can drive on it.....three hours.
Listening to the scanner this morning, someone called the sheriff about being taken by guys sealing driveways. Same truck that was over to her house the other day.
Here's a little bit you can read about the sealer types
http://www.dykespaving.com/blog/types-of-asphalt-sealers/
And I always use the guy that did my driveway to seal mine. That way if there is any major problems, he will cover it. Plus I have sent him enough business, I usually get a free sealing out of it.