Punishments are a strange thing in the BDSM world, as they are often longed for and fantasized about. If you aren't careful, punishment can have the opposite effect. I'd like to point out that there are two types of punishments, the first type are just part of kinky play, and the second type of punishments are an honest deterrence to behavior. I call these fun punishments and serious punishments, respectively. Both have their place, but the community mostly focuses on the playful end of things. Kinky stories, which are usually written by men, are filled with punishments that subs would just love to endure. Whereas serious punishments are harder to find.
Fun punishments should never be given out for something you don't want your sub to do. Only use them playfully, and in ways that your sub knows you are playing. Tone and attitude is extremely important. Make sure you are overly playful and cheery about it so he knows you're not seriously upset. For example, when my pet is massaging my legs and thighs (all the way up please) I'll tell him if he gets hard I'll have to spank him, or make him go down on me, etc. It doesn't even have to make sense as a punishment. You can pick pretty much anything you two enjoy for a fun punishment. All you have to do is treat it like one; tell him he's been a naughty boy and he must live with the consequences. These punishments are a lot of fun, and you can find countless great ideas online.
However, one area often overlooked is real punishment, and that's what I'd like to focus on. I call it Domestic Discipline, but I'm sure that's some sort of misnomer in the BDSM world. Sure, if your sub is horny, then almost any punishment has the potential to make him more horny, but the goal with domestic discipline is behavioral change, and it can be accomplished. To me, this is one of the most over looked perks of being a dominant in a D/s relationship. Most subs love the whole "training" aspect, and those that don't, readily accept it. You get a well behaved sub, and they get what they enjoy, being treated as your pet. Both sides enjoy the power exchange.
When dealing with the serious punishments, avoid punishments that are difficult or hard on you. If something is a lot of trouble, then it's also a punishment for you. The exception of course is if it's something you really enjoy, then it's worth the trouble. Perhaps you really enjoy pegging and your guy hates it, then this is still an acceptable punishment for serious offenses. But most men love pegging, and most women don't get any enjoyment from it. So, again, be careful with what you use as punishments. Don't let your sub trick you into a punishment he actually enjoys.
That said, one thing I've learned over the years is that serious punishments should always have a sexual element to them. You don't want your sub to be angry with you about being punished. Having a sexual element involved connects to him on a low, submissive, and sexual level, and reminds him that training is something he wants as well. This association will also help your sub accept his punishment, even if he feels he's being punished unfairly. While some punishments are solely sexual punishments, it's also fairly easy to add in a sexual element to otherwise normal punishments. For example, one vanilla punishment might be standing in the corner for 15 minutes. To add a sexual element to this, have your sub wear weights from his balls for those 15 minutes as well. If he is to clean the yard as part of a punishment, make him wear a butt plug.
For the most part I prefer to use punishments that are sexual in nature all on their own. My personal favorite is ball spanking. I call it spanking because it even sounds harsh. It's the punishment I most commonly give my husband for breaking any of the "pet rules." The pet rules started out as a list of pet peeves, pun intended, but I've added other offenses to the list, such as not getting the door for me. When he breaks a pet rule, I tell him to get himself ready for a ball spanking. If others are around at the time or we're not at home, at the first chance I get I let him know that he will be getting a ball spanking; then when it's time I tell him to get himself ready. This means he is to undress, secure himself to the bed, and wait for me. If he is hard I wait until he's not hard. When we begin I ask him what he did wrong, if I have to tell him then that's an extra spank to the balls. He then is to tell me it was wrong and that he won't do it again. I start with three spanks for a first time offense and increase it if it happens again, decreasing back down towards three if he hasn't broken that rule it in a while. (You might need to hold his cock out of the way depending on how it lays.) Make him count each slap out loud, an extra slap if he doesn't count quickly enough. With pets new to this you'll have to tell them what to do every step of the way, but they learn quickly, especially if you give them an extra spank for needing to be reminded. All you should need to say is, "go get ready for a ball spanking."
Again, be careful your sub isn't enjoying it more than he's disliking it. There are two types of subs interested in CBT (Cock and Ball Torture). The ones who get harder from it, or prefer they are hard during it, and those that will go soft from it, or don't mind being soft during CBT. I think most tops prefer boys from the first group, but there are a lot from the second. This makes this punishment a poor choice for some subs. (Although it could still work, try it if you're interested.) If you're lucky enough to have a sub from the first group, or you know he doesn't fantasize about this sort of thing, then it's a great punishment. With CBT you usually start light and work your way up. The endorphins slowly build up and your sub can take more and more pain. The trick is to administer the ball slaps before the endorphins kick in. Balls can take a lot of abuse, so you can be very rough with them without damaging them. In fact it takes less pressure to break a rib than to rupture a testicle. As I mentioned earlier, if your sub is erect, wait for him to get soft. Don't start slow. Do it fast, and do it hard. If he's getting an erection, hit him harder. I'll say it again, balls can take a lot. Don't be nice, be serious.
Another serious punishment I often use with my hubby is orgasm denial followed by a ruined orgasm, particularly in the case where he comes when he's not allowed. I feel it fits the crime. He doesn't enjoy going week(s) without being allowed to come, and he knows the resulting orgasm won't be as good as it could have been. So it works as a serious punishment. With different subs you'll need different amounts of time to get the same effect. With some, it just won't work, although you may find a ruined orgasm at the end does the trick. Also, since it's a punishment that occurs over a period of time, I have him tell me why he is not allowed to come each time there's a missed opportunity. During such denials I like to make my subs masturbate more, and will make excuses to play with him just so he has to tell me why he is being punished. I've found the repetition helps prevent repeat offenses.
Dealing with a sub on orgasm denial can be tricky as well. Some subs will ask or even beg for less time in orgasm denial. Ironically, I find these are often the ones who've fantasized about it but never experienced it. If your sub starts asking for a reduced sentence, add a day. They learn quickly, and trust me, it can get on your nerves. If a sub isn't asking for less time, but is still complaining, make a rule that any complaint related to punishment must include a thank you, or you'll add a day. I do these two things and it makes orgasm denial much easier to administer. If he comes during this punishment due to a fault of his own, then we start over and his cock isn't allowed any physical stimulation. And if it happened at his own hands, I also double the time. But this is a last resort as this kind of inactive denial can have a huge emotional effect. I can admit when I'm wrong though, and if he warned me he was close but I was having too much fun teasing him and I made him come, we just start the denial over.
I've had other pets in the past who would intentionally make trouble when I announced this was the punishment. I was surprised that men who love an orgasm so much would want to not have one so badly. But it's about the fantasy for them; when actually playing they almost always want that orgasm. When it comes down to it, many realize it's not what they really wanted, and they regret making trouble. What they really want is for you to take control of their orgasms as part of your control over them. (Which I suggest you do anyway.) The lesson here? Some subs fantasize about punishments that other subs hate. There's no fixed set of what works as a punishment. You just have to try things out and use what you know about your sub.
Getting started is easier than you'd think. Make some rules so your sub isn't surprised by your new approach, but feel free to punish him for other things that really upset or anger you. Make a list of things he's not to do, and when he does something wrong, punish him as soon as possible so he associates it with the punishment. If you prefer to wait, or have to because others are around, do your best to point it out to him at the time. And always remind him during punishment. Make him tell you that what he did was wrong, and that he won't do it again. You may want to start with a small set of rules so it's not overwhelming, but feel free to add things as you go. Even if it's just something that bothers you. For an example of the types of things you can fix, here are a couple of my pet peeves: the toilet left up, an empty toilet paper roll, clothes not in the laundry basket, towels on the floor, plates not in the sink, and trash not taken out when it's full.
A good serious punishment should be sexual in nature or at least have a sexual element, and there's a set protocol or guidelines as to how it's done. Most subs will melt when this approach is used, and it helps avoid arguing and resentment. Pick a punishment that's easy on you, and try it out a few times. If it's not working, try a different punishment. Also keep in mind that you'll get much better results if you're consistent with punishment. With the right approach, your sub will not only behave better, but he's going to be more horny. And that's always good.