For me, having a plan can really minimize my anxiety. Before I go someplace, I research online to make arrangements for activities and things like car rentals. Sometimes I map out directions from the airport to the hotel etc. I create folder will all my important info in it. Some vacations i have even made schedules of what would be going on each day. The Internet is your friend. You can even find detailed maps of airports if that sort of thing stresses you out.

Also focus on what a good time you will have. Although travel can be stressful, there is a lot of fun in it too. SF is a cool city.

Enjoy!
EJ