My experience, especially with some one new to this, is the same as everyone says. Take it slow, slow , slow, and use plenty of lubrication.
Make sure she is relaxed. A drink or two maybe.
Give her a few legshaking orgasms first, to get the juices flowing, i.e oral, toys, or all of the above.
Try talking to her, maybe she just isn't into it? Communication is always a plus.
Good luck,
David