Image from http://compassandcoffeespoons.wordpress.com/
Hopefully these tips will also make your trip more enjoyable and memorable.
1. Wear Comfortable but appropriate shoes
I cannot stress this enough, some shoes WILL make your feet hurt, and no one at that fancy restaurant wants to see your sneakers. If you are going to walk around all day, don't wear high heels or flip flops, but if you plan on going out to dinner after a long day's walk, wear something comfortable that don't scream "basketball court", think nice, flat weekend sneakers like Converse or Keds.
2. A Small point and shoot camera is all you need
If you have a smartphone, you might not even need to bring a camera. A big honking camera around your neck says "I'm a tourist, please take my money" If you don't like the camera on your phone, a small, fits in your pocket sort of camera will be just fine. Unless you are a professional photographer, you shouldn't need anything more, and your neck will thank you too.
3. Take public transportation
Driving somewhere unfamiliar is always a hassle, add a city such as San Francisco to that, and you will begin to hate everything. In San Francisco, there are a lot of crazy streets, one way streets, miles where you are not allowed to turn left, and parking is always an issue. Do yourself a favor and take public transportation. Especially in places where most of the local population relies on public transit, it is generally easier to get around on the train/bus/whatever than driving. You won't have to worry about a rental car and you might discover some new wonderful bistro or coffee shop.
4. Don't be afraid to go off the beaten path
Tourist traps suck. They are expensive, and generally pretty boring compared to the rest of the place you are visiting. San Francisco's Chinatown district is more than just the one street, if you go two blocks away from the main drag, it's like you are in China, the dim sum is cheap and the only English on the menu is the word "each". Most tourists never see this part of Chinatown because they get stuck in the tourist trap. There are literally hundreds of interesting things to see in San Francisco if you venture away from touristy areas. In any city this is the best way to understand a city, go where the locals are, and you will learn why people live there.
5. Ask Questions
Talk to the locals, ask them where a cool bar is, recommendations for cheap things to do on a Friday night, etc. You will learn so much more about a city and maybe even make some new friends in the process. Most people are more than willing to help welcome someone to their city, even if it's just by giving them directions for which bus to take to get to the Golden Gate Bridge.