So in my experience as a Dom I feel it out. I watch porn and then have a dialog with my sub and get there feeling some it. If it's something we both agree on then I learn as much as I can and we practice it safely. I use a strict color code and safe word system in the event anything doesn't work Read more… out.
If your just looking for new things make it up. I one time only communicated to my sub through whistles and finger motions. It was hilarious and we now refer to that roleplay Master. Whistle.
It's just important to feel it out. See what gets your submissives juice flowing. Then exploit it.

So all Vaginas are different. They are for the most part warm and slippery. If your in for awhile you can almost feel the pulse of your partner. There is also a sense of pressure kind of similar to squeezing your index finger in the palm of your hand. Now if your go about knuckle deep and bend your Read more… index finger in a come here motion with you finger pointing up you will feel a spot that is almost ribbed. Seriously you can feel small indentations and its alittle rougher then the surrounding area. That is the Gspot.