2 Hours Ago
In general, patience and persistence helps.
For the sake of discussion, we can think of stimulation on a scale of 1 to 10 where "1" might be the slight physical awareness triggered by slipping panties on and "10" is the irreversible loss of control. In that world, 7 to 9 is the "damp to drenched" range where control is progressively harder because the physical stimulation progressively overwhelms the ability to think or speak. My experience is that it is not possible for an untrained dom and an untrained sub to reliably go from 0 to 9.9 and stop; you don't know she's at 9.8 and counting, she doesn't know how to control herself sufficiently and you end up sending her over the edge.
With training - which requires patience and persistence - you can get there. Some suggestions:
1. make your expectations clear in advance - "you will not cum without permission, when you believe an orgasm is imminent you will use the word 'please,' and if you dare to cum without permission, you will be punished." Then have her repeat those expectations back to you.
2. set aside sufficient time to achieve your goals - not less than an hour, possibly two or three. That means having a bathroom visit before you begin and a glass of water (or clear soda) at hand for later.
3. impede her other senses - you want her entirely focused on the physical sensation you provide and on her reaction to it, which means eliminating other sources of stimulation. At the very least, she needs to be hooded in a dim, quiet room. Ideally she should be bound and wearing insertable earplugs.
4. begin simply by taking her to "7" (noticeable increasing in lubrication, some increase in respiration) and stopping. Never break physical contact with her, simply move to stroking her inner thighs, stomach or breasts so that she stays at a simmer. After a couple minutes, take to back to a "7," keep her there a minute longer and then let her drop. Your goals are to gain an intimate knowledge of her physical reactions, which will become progressively accelerated, and to increase her need. By bits, move her up to 7.5, then 7.5 longer, 8.0, then 8.0 longer. If she gets ahead of herself, simply pinch her labia or clit hard enough to get her attention. Speak firmly to her, then resume.
5. once you're comfortable with your ability to reach "9," introduce pain into the equation by slowly and firmly slapping her pussy. (I'll get around to writing about the underlying process of neural entrainment at some point.) Start at a stroke every two seconds and progress to one per second; at first she'll be surprised by the pain, then by the strength of her reaction to it. (Practice on yourself to get the impact right.) Take her to "9" with slapping, then twice more with stroking. As you accelerate either, you move her toward "10."
How many times can you push her toward the edge? Maybe only 20 or 30 times at first; 40 or 50 is achievable with time and a certain perverse delight on your part. From there it's just a small step to more-maddening delights.
For what that's worth,