In any kind of BDSM context, many people have very precise ideas on how to perform various kinds of punishments. The list is basically neverending, like spanking, needles, clamps, electro torture, whips, sticks, and all the like.
To couples who mostly engange in "SM" in its stricter meainig, those punishments are actually what they are interested in. A masochistic partner actually likes to be punished, and depending on the level of punishment and the level of masochism, the punishment is actually enjoyed, looked forward to and/or actively being asked for.
However, getting back to my much enjoyed and previously blogged about training in a more D/s like setup, a punishment needs to be an actual punishment. I think any form of education/training is most successful if there are both, punishment and rewards.
Depending on the submissive/masochistic partner, I've discovered that there can be multiple quite distinct reasons for accepting and in one way or the other 'liking' punishment.
The former kind of mostly masochistic group of people derive pure enjoyment/lust from the pain that is experienced as part of the punishment. It's - I would at least suggest that - a mostly physical thing. Sexual arousal from pain.
The latter group, I'd say they are mostly submissive, actually enjoys/accepts the punishment as a consequence of them doing something wrong. They don't actually enjoy the actual pain. Rather, they see it as a part of the power that the dominant partner is able to exert over them. And they can enjoy being punished as part of the process to be more like their dom/master would like them to be.
As usual, everybody is different, and these are just my very personal observations over some time now. And many 'bottoms' will actualy be part of both groups, to some degree. But I guess you get my point.
So especially, for that latter group of mostly submissive individuals, there also needs to be some form of real reward. An obvios (and obviously easy, for the dominant partner) way is to define reward as absence or reduction of punishment, restriction or predicament.
So lets assume the submissive partner has to endure whatever restriction to please her partner, such as e.g. feet-killing high heels, a tightly laced corset, gag, [butt] plug, clamps, whatever. Then it's easy to reward any desirable behavour by loosening/removing that obligation.
Also, in my humbly opionion, verbal rewards are extremely important. Let the submissive partner know that you are extremely happy with a particular performance, that you are proud of your good girl/slave/pet/... After all, she voluntarily submits herself to the dominant partner, in order to please him, and to make him happy (and be happy because she can make him most happy in that way)!
Another option which I find particularly tempting, is to consider sexual pleasure/satisfaction as a reward. This obviously varies with the partner, but at least with partners who have a healty to strong sexual drive this can work quite well. So in such a setup, the dominant partner can tell the submissive one that she will only get fucked as a reward if she performs her [however defined] duties well before. Sometimes her motivation can be enhanced by making sure she is/gets already quite hot and horny while performing the actual duty (by having to wear some sex toy or whateever else is keeping her aroused but does not provide the chance to orgasm.
Obviously this will only work if the dominant partner can actually control himself from not taking her just because of his sexual desire (before she has performed whatever duties she was supposed to perform). I personally have to admit that I absolutely never had any problems resisting that temptation, but I've heared of men who have ;) This can also give another twist to the overall game. Lets presume she wants to get fucked, and thus takes care of her duties, and wants to be rewarded. If he is watching her, she can behave (if permitted) in a particularly slutty way, show herself off, behave even more in the way she knows that turns him on :)
This kind of 'reward by sexual pleasure' play will probably find its strongest form in couples who engage in chasity belts or other chasity devices. I personally haven't really got any experience with it, and it isn't something that is on the top of the list of things I like to try. But sounds reasonably interesting, still :)
Which brings us to another topic, that is not at all a reward, but somehow relates to sexual pleasure in a D/s setup, oto: It's one of my personal favourites and called 'orgasm control'. Allowing the submissive partner only to orgasm after having asked and being granted permission to do so. Yes, sometimes that can be hard for her. But hey, who said it's going to be easy :)