Funny enough I bought my wife fifty shades of grey as well, and she now wants to try some "kinky fuckery" as well... What Kuve says is right though all the usual relationship rules apply. You really need to talk through with your wife what she enjoyed about the session and what she didn't enjoy as her feedback can provide ideas for you. You should also talk about the kind of stuff you both would like to try, and perhaps go shopping together for some toys and gear as this again will give you ideas, and you'll begin to establish both of your limits (yes Dom's have limits too).

I would advise you take things slowly and very lightly at first, just explore gradualy, its ALWAYS better to leave her wanting more than to push her too far and risk scaring her away. In addition to Kuve's recomended books I would also recomend SM101 by Jay Weisman, and The Loving Dominant by John Warren and Libby Warren.

I hope all goes well for you and both of you continue to develop your relationship together. Good Luck