Wheelies can be fun, but make sure you do them safely and in a place where they're legal. First and foremost, you do wheelies by the feel and sound of the engine, not by what the tachometer says. Everyone has different power and sprocket setups, plus you don't need to be looking at your tach. Pay attention to the road.
1. First step is a basic "roll on power wheelie". Basically you need a bike with enough power to raise the front wheel off the ground with simple acceleration. You need to get comfortable with the front end getting "light". Most stock bikes won't be able to do this without some modification. You can also try getting the bike up to a good speed in first gear(around 10-20 kph), once you reach the powerband