We've all done it. Either you've lost your footing on uneven ground, cocked up a U-turn or your bike's been knocked over by an inconsiderate driver, at one time or another you'll need to pick your bike up off the floor.
Unless your bike is a low capacity scooter, picking up something that probably weighs more than your own bodyweight is a hazard to your health. The first step is to kill the engine. The only thing more embarrassing then dropping your bike is dropping your bike and attempting to pick it up with a screaming engine. With the bike on the ground, turn the bars away from the side it's fallen.
If the bike is on its left side turn the bars to the right. Holding the end of the left handlebar in your right hand, squat down with your back to the bike. With your left hand find something solid to grab onto, a frame rail is ideal, bodywork isn't strong enough.
Keeping your back and arms straight, use your legs to lift the bike from the ground. As soon as the bike is off the ground you can use your backside to support and aid the lifting by pushing the bike up and away from you.
Using this method, most people can pick up even the heaviest of motorcycles.
You're using the most efficient leverage on the bike (the handlebar) and the biggest muscles on your body (the legs).
If you intend to ride the bike check thoroughly to make sure there's no levers missing or holes in engine casings.