Driving in Havana and its environs isn't as daunting as you might think; there are relatively few cars on the roads, and most drivers aren't overly aggressive. Remain alert and flexible and watch out for bicycles, ciclo-taxis, and coco-taxis—not to mention pedestrians looking for botellas (rides). Road surfaces are uneven, so if you drive, keep your eyes glued to the pavement. Cubans beep their horns often, though rarely in a belligerent way; this is a courteous way to let other drivers know you're coming through.
Parking isn't generally a problem in Havana as there are still relatively few automobiles circulating. Even around Plaza de las Armas or Plaza de San Francisco de Asís it's usually possible to find a parking spot. You will, however, encounter freelance parking attendants who will keep an eye on your car for a dollar up front, a bargain automobile-security system.