Do not try to do a wheely they are dangerous… Do not mess your self up and say you read my crap and it made you fall off…Read at your own risk – do not try it.
So – Sit well back, get moving at a gentle pace, if you go too slow the bike will wobble, if the front wheel is spinning it will act as a big gyroscope and keep the bike from falling to the side, so start faster than walking pace, and the faster you go the more stable the wheely will be, around 25mph feels good but if you fall off the back at that speed you are going to get hurt and the bike will do too much damage to itself or the stuff around you or you. When you are at a steady speed in at the point in the rev range where you might change up if you were being gentle, but instead give it some whoosh with the throttle and pull up on the bars a little, if you have a less powerful bike you might need to slip the clutch a little give it max revs and just let it back on quite sharply. Finally if you just drop your self forward just as you come to the point where you would like to start and the pull your self back and the bike too, you will lighten the front of the bike and it will come up quite nicely. Depending on how you front shocks are set, i.e. if they are quite springy and no too slow and absorbing, you can bounce the front up by compressing into the ground, try to aim you weight at a point just behind the contact patch of the front wheel.
Any of these methods will bring the front wheel up in the air. I like to stand as the bike comes up and hold the bars up close to my chest, (you will not get it there but the idea is to try and not to let your arms go strait as that will either result in a low wheely or you will be leaning way back looking at the sky) then keep it balanced from going up more or loosing it: with little adjustments of the gas and do not be tempted to give it a big handful of power if it starts to go down, you need to use tiny adjustments and a very even throttle, in the same vein, if it goes too far back do not stamp on the rear brake or it will drop like a rock and you will probably get your self tangled in your own handle bars as it smashes down and bottoms out. Instead just let the power off a little and it should come down without a big compression, sort of sit a bit as it drops and you should feel in control all the way though. While you are up do not be tempted touch the front brake or steer with the bars they will both make you loose it until you have really good feel. You can change gear but best to do it with no clutch and leave the throttle alone till you have got right into the next gear. You can steer a bit through the pegs, this is much easier that you think, and hey presto you are a wheelie king. It takes a few afternoons to get the whole thing dialed in nicely and practice on a nice smooth field, it is not much harder to balance than on the road but a lot softer for the bike if you mess it up, you will probably not go over the back (that is the mistake of massive over confidence or no ability to control the clutch, the average person over 15years old will usually back off the gas sharply at anything over 30 degrees; as it will feel much more like 90% from the riders perspective at first, as you get better you may scare yourself one or twice but if you were video these frights; you would see that you were never that close to loosing it. If you hear the numberplate drag along the grass you are getting pretty good!