This question is frequently posted on collarme, a BDSM site I belong to. Asking some strangers on the Internet to provide a road map to kinkify a conventional partner implies there’s a magic bullet. There isn't. It's way hard. Every relationship, be it vanilla or kink, is specific and unique to those particular partners. The answer to the conversion question is as complex as the people involved.
Sometimes I’ll reply to these posts with general suggestions on how to "turn" a partner, because I’ve done it. Here's the difficulty: Success in kinkification takes character attributes nearly as scarce as that mythical magic bullet: patience and empathy and flexibility. And even with those traits, turning may never work. When I offer this advice on collarme, the response is often hostile. Conversion is supposed to be easy.
I also know what not to do. Here are the most common mistakes:
1. Entitlement. (“I want what I want. I’m more important than you.”) Good luck with that approach.
2. Bullying. (“This is what I want. Give it to me”). That’s a sure way to force the end of the relationship, or maybe even get a surprise visit by the cops.
3. Martyrdom. (“If you loved me, you would…”) Manipulation doesn’t work in the long run.
4. Childish tantrums and ultimatums. (“I refuse to live the rest my life as a vanilla.”) Be careful what you wish for.
Initiating "turning" requires small, slow steps. Perhaps your mate is curious about a particular action? Maybe your partner is motivated by your excitement, or the naughty danger? Your mate must be the leader in the first explorations. Offer a multitude of options, be a gentle guide. What fantasies does your partner have? Role-play? Bondage? Indulge them. Make it fun and sexy. And most of all, appreciate his or her efforts.