How funny, I am literally in sf right now visiting! On phone so keeping this short, but here are my thoughts (I come here quite a bit):
--def bring a jacket, something that closes, has long sleeves, pref wind resistant. I brought a leather jacket. I've seen a bunch of those, and also popular are gear type jackets (like lulu lemon type).
--comfortable, flat shoes that fasten to your feet securely. Lots of steep hills!
--layers! I personally like to bring pants that can be rolled up so they can be worn long or cropped, and leggings to go under my skirts (for warmth and wind)
--a scarf is always a good idea and looks chic too.
--if you're planning to leave the city at all be aware that places like South Bay and napa are a lot warmer (but still cool down at night).
For a four day trip I have (in small carry on):
-1 jeans (can be cuffed up)
-I linen pants (ditto)
-1 skirt (plus leggings)
-1 thinnish fashion sweatshirt
-1 linen sweater + cami
-1 ss blouse
-1 sleeveless tunic
-sack dress (worn to work in boiling hot Boston and then on plane)
-casual knit moto jacket (this feels more like a cardi and can be layered under the leather jacket)
-leather jacket
-denim jacket
-flat oxfords
-comfy flat sandals
-dress, shoes, and hat for the wedding I'm attending.
-2 scarves
Note I'm planning on spending some time in the South Bay (so warmer) and I have a formal event to attend.
Hope this helps!
As for food, go to the mission district and get burritos! I also like wandering thru the ferry market and getting food at the various stands.