In order to learn wheelie well and safely, you definitely need time! My personal experience is that if you practice 2-3 times a week, for at least an hour each time, you will progress quickly.
Of course, for this you need to have a WHEELIEMATE wheelie trainer, which beside the safety instructions, protects you from looping.
It is recommended to develop a kind of training routine:
1. you roll comfortably to the safe and traffic-free area where you will start the practice
2. you perform clutch handling exercises (you start on a slight incline, your legs may hang sideways and on the incline you hold the bike in one place by sliding the clutch only, but the bike does not move)
3. in 2nd and 3rd gears, without a clutch, you try wheelie (with throttle only)
4. practice in 3rd gear with clutch
5. practice with the clutch in 2nd gear
6. practice pivot turn in 1st gear
7. finally is up to you, how you feel when shift from 2nd to 3rd or from 3rd to 4th, so this is the shift practice
With proper practice, you will be able to reach an excellent level in 2-3 months!