what's the proper thing to say....

That's hard. One thing not to say is "I know how you feel" especially if you don't. Many times when someone is mourning, they are not looking for some deep answer or response, they just want a friend to hold thier hand and listen to them. For someone to be supportive, even if they don't completely understand how it feels. ALso, sometimes they need someone to just stand there with them, as they make small talk with distant relatives, and for someone to help them and head off any awkward situations.. because not all people are sensitive or sensible about what they say to someone who is grieving. Another good Idea, Someone who is mourning, usually forgets simple things, like to eat or drink.. or sleep and they need thier streangth as crying/weeping takes alot out of a person.. so bring them food or drink.. remind them that they need rest.. and just try to be thier for them. .Good luck to you.