Step1
Adjust the seat. The average unicycle is about as high as the average bicycle. Adjust the height to a comfortable level--about where you would want to ride a bike, but a little lower. Your legs should still be bent when the pedal is at the bottom of its revolution. At their highest, your legs should form an angle less than 90 degrees--about 70 degrees if you're counting.
Step2
Practice sitting on it next to a wall. On level ground, climb on the seat, using the wall to brace yourself. The biggest risk is that the seat will fall forward or backward, depending on your weight distribution. Don't try going anywhere, just get comfortable sitting on it.
Step3
Work on your balance. Put equal pressure on the pedals with each foot. Your feet should be about level but staggered, with the pedals sitting halfway through their motion. If you feel the seat rocking forward, put a little more pressure on your back foot. If you feel the seat falling backward, put pressure on your front foot. Again, don't try going anywhere just yet. Simply try to maintain balance.
Step4
Using the wall again, try to ride forward and backward. You're probably going to fall at first. If you feel the unicycle falling, just fall onto your feet and let the thing crash to the ground.
Step5
Venture off on your own. Try riding around a bit on flat land. Once you've gotten the hang of it, try going uphill and downhill.
Step6
Jump off a curb. At this point, we're assuming you can effectively ride the thing on level ground. Now, find an average curb and simply ride off it. You're going to fall, and it's going to hurt. But by your third time, you should have an idea of the impact and how to prepare for it. Once you've mastered slowly falling off the curb, step up the pace.
Step7
Jump up the curb. This isn't easy, but if you're going to be a showboat, then you'd better know how to do it. This is the foundation of unicycle tricks. On a bike, you have handles to help you "bunny hop"--not here. Place your dominant hand on the back of the seat, fingers pointing down. Grip it with your palm. Think of it as riding a bucking bronco. Next, squeeze your thighs together by flexing your gluteus muscles while slightly bringing your legs in together.
Step8
Invent tricks. If you can successfully jump off stuff and onto stuff, then you can likely jump ramps or, if they're brave enough, your friends.