If you haven’t Airbnb-ed a place in some other district and find yourself near Fisherman’s Wharf, the first tip is to get out of there. Union Square is still touristy, but it’s worth seeing and good for a stroll. Honey Honey is a solid breakfast spot.
Hopefully you’ve had enough sense to come to the city when the crowds are sparse, but can still appreciate some decent weather; October is a good middle ground. The reason why will become apparent as you walk down to Powell Street Station and check out the line waiting for the cable cars; during the summer, it’s not unusual to wait a couple hours to ride.