Taxi's: usually a little over 10% for a large fare, but round up to the most convenient number. If it's $5, I give $6. If it's $10, I'll give $12. Fare from the airport is usually $33-$34. I'll give them $40. But if the fare is $35, I'll still give them $40. If it is $36-$37, I'll give them $42.

Give what you think is reasonable and fare. No $5 minimum, no 20% minimum. I have never heard of that.

Since I am local, when the taxi tries to jack me with the fare by taking some ridiculously circuitous route (which they have done and I've called them on it), I give them zero tip. Many times, I just call car service because it's a flat rate; there are no games. When you arrive in a city, and you know the cab driver jacks you hard with the crazy long route, it just leaves a really bad taste in your mouth. You know the extra little bit of money is not that critical, but the whole principle of being 'taken for a ride' just doesn't sit well. I hate how cab drivers try to squeeze more money out of you like that. It's analogous to cutting in line, riding the bus without paying, cheating on the test. Just a morally bad thing to do, and it makes the start of your trip just awful.

Free shuttle service: General rule is $1 per bag.

Luggage hold: $1 per bag.

As a college student, you cannot be expected to be tipping like Rockefeller or Trump. Just tip what you think is fare and reasonable.

For fun cheap things: Golden gate bridge, golden gate park, chinatown, north beach, union square.