You've almost got it. Just take off that last part after the slash, and you have your question: How do you start again with someone else?
Exactly the same way you'd start a new vanilla relationship. You meet the person, you talk to them, you tell them about yourself and you ask them about themselves. If you don't like them right away, good bye, move on. If you both like each other enough for a second meeting, great!
Though the things you discuss might include BDSM things (though they might not), the way you pursue it is the same. Listen carefully, be honest, and trust your instincts. It's like a first date with anybody. You're both feeling each other out to see where it goes, if anywhere at all.
Good luck, and I hope you find a new partner who you are happy with!