in the beginning i read books and journaled. then i began blogging and met other babylost mamas online. i also attend a support group that meets once a month.
i think the best way to support a grieving mother is to help with all of the day to day things so that she doesn't have to deal with them (cooking meals, driving the other children places, making sure she has time to spend alone with her husband, etc.). talking about the baby, using the baby's name. hearing your baby's name is so amazing because it validates that there was a baby and somebody else remembers. i've found pictures or artwork that other's have made with xavier's name to be very healing. give a grieving mother lots of cards, not just one right after the baby dies, but every so often when you are thinking of her send her a card snail mail or jot her a quick e-mail. mention the baby by name, i know i already said this, but it is so important (she probably wants to talk about her baby)!
i hope this is helpful to someone. *HUGS*