Instructions on how to ride a motorcycle are easy to come by, but practice is what will make you a good rider. Consider taking motorcycle driving classes, which will give you knowledge and first-hand experience before you hit the open road by yourself.
If you know somebody who is an experienced biker, enlist her help in showing you how to sit on your bike, hold it up and turn it on. Although you can follow these directions yourself, a biker with a lot of experience will be able to point out anything you're doing wrong and share tips with you to make learning easier.
You should make sure that you're able to hold your bike up, preferably before you buy it. Don't get a bike that is too heavy for you, but keep in mind that you'll become accustomed to holding a bike up at stop lights.
When you know you can handle your bike, try turning it on. To do this, make sure your motorcycle is in neutral and turn on the power switch, the fuel switch and the ignition. Pull out the choke and then push the ignition button. Let your motorcycle warm up for a few minutes, especially in colder weather, before you start to drive it.
Next you'll need to learn how to shift. On a standard motorcycle the neutral gear will be between first and second gear, with first being below neutral and second through fifth being above neutral. On a sports bike this is reversed, but essentially everything else is the same.
Hold the clutch in as you shift, into first from neutral and then upwards as you need to. You'll be able to feel when it's necessary to shift gears, as your bike's engine will be revving high.
Never downshift when you're driving a motorcycle. Unlike in a car, to slow down in a motorcycle you just hit the brakes. Downshifting is reserved for when you're actually stopped and are putting the motorcycle into first or neutral.
Make sure that you're comfortable handling your motorcycle before you venture out on it. Ask questions if you're uncertain about anything and always, always wear a helmet.