I love getting bitten. In fact, it's the start of our BDSM journey.
Advice....? Make sure you listen when she communicates to you that it's too hard. This could be just "Owe that hurts, stop it," or a safe word just some communication that is understood between the two of you. I like to be bitten on my neck, breasts, buttocks and inner thigh.
Just like anything else during sex, open communication is important. Have fun!
Oh, and if she likes being bit... there's a good chance she will bite you. So be ready for it, and be sure to communicate to her if you like it or not. My husband isn't a fan, but he puts up with it because he knows that sometimes I just can't help it. LOL