From the first question of whether you would like to play to the day after a scene, an open dialogue between play partners is necessary. The simplest way to get what you want and need out of a scene or D/s relationship is to always negotiate, and negotiate often.
Finding someone whose kinks and boundaries overlap involves being able to communicate your needs, fantasies and limits. Talk openly about what excites you, what makes you uncomfortable, how you respond emotionally and physically to play, and the kinks that have piqued your curiosity. If you're newly initiated to the world of BDSM, you need to be ready to communicate in and out of scene when your interests and limits change as you discover them as well as any uncertainty that you may have.
Expressing your feelings and emotional response is important too. If you feel nervous or unprepared it can help to discuss what aspects of a scene are giving you the jitters, give you time to ask last minute questions and feel out specific boundaries. For example, you might be into bondage, but you cannot stand tie that completely immobilize you because they make you feel trapped and panicky. Setting a boundary around this response will keep your scene from unravelling by avoiding a particular trigger. If certain scenes you want to participate in elicit a deep emotional response like giggle fits or crying, you need to communicate this to your partners before you play so they can have a better idea of how to read your reactions while they get to know you.
Knowing what to say is great, but when will all this talk take place? Will a scene come to a complete halt while you negotiate adjusting bondage? How do you keep from scaring your prospective Mistress away with a drawn out recital of kinks, limits and scene ideas or make it seem you are trying to micromanage the next scene over coffee? Negotiation is not always a serious business, you can figure out ways to make discussing boundaries, fantasies and needs in and out of scene, even in a role play without breaking character. There's always a certain amount of playful banter back and forth when getting a feel for one another and how well you'd play, you can insert negotiation into your flirty dialogue bit by bit, setting a precedent for open and honest communication to get what you both want in your future play.