There are three San Francisco cable car lines. Two end up at Fisherman's Wharf and both begin at Powell and Market Streets. The Powell-Mason line goes up Nob Hill and heads to Bay Street while the Powell-Hyde line traverses Nob Hill and Russian Hill, arriving near Ghirardelli Square. The California Street line, which can be picked up at Van Ness Avenue or near the Embarcadero, runs through the Financial District and Chinatown.
There are a few rules and courtesies to keep in mind, which only apply if you're getting on a cable car from a stop along a route as opposed to the end of the line. It's important to wait on the sidewalk and wave to the gripman to let him or her know that you'd like to board. Make sure the cable car has come to a complete stop before doing so. You can board on either side of the car but there must be enough room. If not, please wait for the next one.