Hi saluki--how are you???
You may have made your shiva call already, but if not, these might be helpful.
http://www.interfaithfamily.com/life...iva_Call.shtml http://www.ehow.com/how_12302_pay-shiva-call.html http://www.myjewishlearning.com/life...gshivacall.htm
A lot of it depends on the family's religious background. If they are orthodox, you can expect a stricter observance (i.e., mirrors in the house covered, family might not bathe during shiva period, family might sit on the floor). A conservative or reform family might do it in a more relaxed way.
There's no need to bring anything, although if she's a close friend, it may be nice to bring a tray of food or sweets for the mourners and visitors to have. This is certainly not necessary.
You don't have to wear black or get too dressed up. Somber "business casual" type clothes are appropriate, unless you're visiting right after the funeral (in which case, wear whatever you're wearing to the funeral). Again, if its an orthodox family, just make sure you're covered up and not showing too much skin.
Oh, you may see a pitcher or bowl of water outside the front door. If so, it's a nice gesture to use a bit of it to wash your hands before entering the home.
I'm sure others will add some...
Best,
Shari