I agree that the only thing we can really do is provide friendship and comfort to the best of our ability. In most cases we can't solve the problems, it is beyond our ability and control. To offer friendship, to listen and do what we can to comfort is the best we can do.
and I totally agree with NOT saying "this too shall pass" the hurt they are feeling is fresh and real and they don't need someone to make it sound like it's nothing.
Alot of times it's common sense that tells us what to do when someone is in need of help. If they are hungry, in need of shelter or sick. We should all know by instinct how to help and what to do.
But if it's a situation like a loss of a loved one or a diagnosis of a terminal illness, that can be confusing for us as humans what to say, how to help and that is natural. I have a family member that was diagnosed with non hodgkins lymphoma a year ago, after going through a divorce, and the only thing I could do for her is to let her cry, scream and vent. Hold her hand when she wanted that and let her scream and be her kicking board. Remembering that they aren't saying those mean things to YOU they are saying them to the situation or the person that hurt them. pray with them if they ask.