The biting stage can be very trying hun, i know i went through it three times with mine :shock:
the old sayings are true hun, perseverance with this one, the biting back does work.
The trick is to stand firm and let them know its naughty and that it hurts and if they do it to you you will do it back twice as hard.
Dont let them see you laughing as this will only encourage them, stand firm and put on your gruff mammy dicipline voice and remain adament, eventually they will give in and come looking for sympathy, dont give in, hold them away and let them know how naughty it is for a few minutes.
When you do except them for a cuddle tell them that its wrong to hurt mammy or whoever and that its much nicer to be mammys good girl instead of her naughty girl ect.
I bet i sound like a right old nasty eh lol, but hey it worked for mine and all my nephews, nieces and any other kids that have come into our lives xxx