Cleaning the drive is the worst part of doing the job.
Sweep it, blow it and get ALL of the dirt off. Then treat EVERY oil or gas spill with chemicals or you can gently burn them with a torch. The chem route is safer for your drive because you can burn asphalt, and you dont want that.
If you DYI it this time of the year, clean it the day before and start sealing early AM (6) when everything is cool. The sealer will start to set when it is hot and you really have to move on it. Cool is better.
Just pour it out of the can and run it in a winrow with a squeegee and follow with a medium bristle broom to rub it in. You can leave swirlies in it with the broom if you want. Some folks like the look, or rub it in and just pull it straight. Get a 8in whitewash brush to do near the garage and any other feature. Make sure you do the sides of the blacktop also.