Riding ponies are ponygirls or ponyboys who are ridden by their Mistresses (or Masters, Trainers, Owners, (Exercise) Riders, etc.). Two legged and four legged riding ponies are both quite common, though a special saddle for two legged riding ponies makes it easier for both pony and rider.
Four legged riding ponies can also be ridden in a saddle designed especially for ponyplay (several retailers sell these) or they can be ridden in a bio-pony (a bio-horse size saddle tends to be too big for the back of a ponyboy or ponygirl) saddle (and plus it looks hot).
Personally, I like being ridden in a real pony saddle. aside from that extra touch of authenticity, real pony saddles (the good ones at least) are quite comfortable and have nice padded leather on the bottom where it sits on the pony's back. You can look in my saddles section for more information on saddles and how to fit them.
Four legged riding ponies might also benefit from a pair of knee pads/guards, which can help the pony's knees from getting banged up and just make the pony more comfortable. Additionally, a pair of spurs for the rider can make things more fun and interesting, though spurs should be reserved for riders who know how to properly use them. Using spurs improperly can result in serious damage (see my section on spurs for more information). Aside from that, riding ponies do not need any other specialized tack. A bit (with or without bridle) and reins are pretty standard, as is a riding crop and tail. Riding ponies can also wear a harness and various other pieces of equipment. You can look at my tack section for some of the various pieces of ponyplay equipment out there.
Riding ponies also need to be in good physical health to carry another person on their backs; a good exercise program is recommended for riding ponies as well. Riding ponies should also be sure that they do not have any back and neck issues which could be exacerbated from being ridden. Carrying another person, whether it be on two or four legs, is very strenuous work and can put a good deal of strain on the back. It is best to think about any existing back or neck problems prior to jumping in to possibly prevent making any problems worse.
Riding a Four Legged Pony
Riding a four legged pony is very similar to riding a horse, and so a lot of information applicable to riding bio-equines that can be found all over the web can be translated into riding a ponygirl or ponyboy. Of course, there are some important differences such as the disparity in height of ponygirl or ponyboy and a bio-equine. This makes it more difficult to apply leg aids (including using spurs) when riding a human pony. Also, a four legged pony with rider may not be able to effectively perform all the gaits, especially the faster ones like gallop and canter.
Once your pony is all tacked up and ready to ride, mount him/her and take the reins. I prefer to hold one rein in each hand, but it is perfectly fine to hold both reins in one hand. It's also not a bad idea to carry crop. Take up the slack in the reins and keep a small amount of contact (pressure) on the reins (somewhere between 1-5lbs seems good). To move forward apply pressure with your legs and then release (you can also use voice commands such as "walk on," or you can cluck to your pony). If your pony does not respond to these aids, apply more pressure with your legs and release and flick the crop on the pony's butt (and/or use spurs if you are wearing them -- but be careful with spurs). To use your legs effectively, you should squeeze, then release. You can repeat this as many times as necessary, and with increasing force. Once the pony walks off, you should stop applying the leg aids.
Once moving forward, the pony should remain at a constant speed until you instruct him otherwise. If your pony changes speed and you did not instruct him to, then you should correct him immediately. A pony should be able to maintain gait and pace without continuous input from the driver or trainer. To speed up, squeeze and release with your legs, use voice commands, or use the crop if necessary.
Steer the pony with the reins. Applying more pressure to one rein tells the pony you want to go in that direction (i.e. to go left, apply more pressure to (pull on) the left rein). If the pony is not responsive (or not as responsive as you would like) to the reins, then you can use the correct to correct him. For example, if you are applying pressure on the left rein to go left, and the pony is not listening, then give the pony a flick with the crop on the pony's right shoulder - do not flick the pony on the butt since the pony will take this as a signal to speed up. Flicking the crop on the pony's right shoulder tells the pony to move that shoulder away from the crop (i.e. to the left). You may also like to apply pressure with your right leg on the pony's right side to reinforce what you are asking and get the pony the move his whole body to the left.
To slow down, apply gentle rein pressure evenly to both reins, then release. If that does not elicit a strong enough response, apply more rein pressure then release. The amount of rein pressure applied will dictate how much the pony slows. You may not always want the pony to drop down a gait upon application of the reins; it is sometimes necessary to slow a pony's pace, while maintaining gait. Thus, it is important during training to make it clear that slow down, does not necessarily translate into dropping down a gait. Also, some ponies will be more sensitive to rein pressure than others. Moreover, the type of bit and bridle the pony is wearing can also have a significant effect on how sensitive a pony is to rein pressure. Keep this in mind when working with new ponies or using new tack on a pony.
If a pony is running away with you (this seems a little ridiculous, but I suppose it could happen), you can "bend" him off for an emergency stop. To do this, run your hand down one rein (either one; left or right doesn't really matter) until you are holding the rein right near the bit. With your hand all the way down the rein near the bit, pull the rein up and towards you. This will force the pony to bend to a great degree and will stop him very quickly.
To back up, you must first halt the pony. At the halt, begin applying pressure evenly to both reins. Increase the rein pressure until the pony begins to back up. Once the pony has backed up to your satisfaction, release the pressure on the reins and tell the pony to "whoa."
Riding a Two Legged Pony
Riding a two legged pony is, in some ways, easier than riding a four legged pony.