HBO has provided a lovely family tree with a little description to help identify who is who. Very helpful for those who struggle a bit with the names or just needed a refresher (it looks to be spoiler free).
Hopefully it’ll be updated when season 2 comes around. Likewise there is also an interactive map outlining the plot of season 1 (which doesn’t seem to be as Spoiler free) and the locations each episode takes place.
http://viewers-guide.hbo.com/game-of-thrones/#!/guide/houses/