2.1 Right Arm and Hand Position video
Tunefox Guitar Lesson #2
This lesson will teach you how to position your guitar so your right arm and hand will be in the correct position for strumming and flat picking.
This may be completely obvious but you'll want to position your guitar so it's on the same side as your strumming hand (watch the video lesson for a visual). Your right arm should go over the guitar so that your wrist is hovering above the bridge. Holding the guitar on your lap should feel pretty comfortable but if your guitar is big it may be a little awkward at first. If this is the case, try some smaller guitar body types like OO or OOO.