when i started to try and wheelie i was having trouble also. a mate of mine just seemed to pick it up straight away. i mean he just lifted the front end and pulled a minger straight away. sickened me no end. i ask how he did it and it worked for him and with practice it worked for me too.
clutch it up in 2nd, first is too much too aggressive. then the trick is to apply pressure to the gear lever, as in try and change gear. because you are still accelerating the gear box is under load and therefore wont change, when you start to rev out you need to be right up there. at this point like tmoney1 said just twitch you wrist, dont twist it it will be too much. because you take the load off the gearbox it will now change gear, there is no need to use the clutch, because you were up there you should of only dropped a bit, and because you only twitch you dont loose that much hight either. then repeat the process till you are doing a 140 mono in forth.
hope this helped you like it did me.