The most difficult problem with your car in San Francisco will be parking. Parking throughout the city is extremely scarce. Garages, where they are available, are quite expensive ($20-30/day downtown). San Francisco has some of the strictest parking laws and enforcement in the country. For day trips into the city, consider a park-and-ride at a Peninsula Caltrain station, at a Peninsula BART station, or at an East Bay BART station. Another option is to reserve parking in advance using GottaPark.
When parking on a hill (and there are many of them in San Francisco), remember to always apply that parking brake and turn your wheels so that the tires are against the curb (Facing uphill, the front wheels should be turned out until the tires are resting against the curb. Facing downhill, the front wheels should be turned in so that they are set against the curb). Failure to park properly doesn't just run the risk of having your car roll downhill, but it is also against the law and you may be ticketed.
Motorcycles and scooters are a common sight on San Francisco streets; in fact, San Francisco is known as one of the most motorcycle-friendly places in the U.S.. Street parking for motorcycles is plentiful and relatively inexpensive ($0.40 to $0.70 an hour), but note that parking on sidewalks is usually illegal. There are several motorcycle rental shops, along with many dealers, service shops, and motorcyclist hangouts. As elsewhere in California, motorcyclists must wear helmets. Motorcycle theft is a problem; always use a disk lock or secure your bike to a stationary object using a cable or chain.