So I've been learning how to wheelie, getting pretty decent now. At first, for a few weeks, it was real frustrating, I was having no problem popping the front up, in fact, I was bringing it too far up where I couldn't maintain balance or forward speed. A lot of the videos said to start in an easy gear, but that just made it too easy to bring the front end up with popping and pedaling, and not enough to make me go forward. When I tried a higher gear, didn't bring the front end up as far, it "clicked", and all of a sudden I was doing wheelies. I started on my fat-bike with the biggest contact patch, 5" tires. Now I'm a different one with 3.5-ish tires, it's definitely harder, but I'm about as good as I was before I switched bikes. Getting the hang of downhill wheelies pretty well (balance point further back, using the brake to keep the bike from running away, etc.). Was getting pretty good at steering on the first bike, I can steer, but it's not the easiest thing. Steering was definitely the 2nd breakthrough.
It's much harder on my enduro rig, although I tried on my XC race bike today and it was actually much easier than I was anticipating, I was able to hold wheelies in the parking lot, so it's definitely transferring.
I want to get real solid with wheelies, and then move to manuals.
I don't find it's necessary to start on grass or whatever, your brake will bring you down. There is definitely a cliff to get over though in terms of understanding how to pop to the balance point, you aren't going past that, but at first with no preconception of what it is, it's understandable how big of a leap of faith it is. Once you get better, you can start doing it on more varied surfaces, going down and up little ramps, or over speed-bumps, similar. I gotta stop doing it across intersections, probably going to get hit soon.
I watched videos, practiced. Take days off in between practice, but make a schedule where you practice at regular intervals. It'll be frustrating, but you have to keep at it. As those muscles get stronger and more toned, your practice can get longer. Many videos had important elements. Many videos had things that I didn't find helpful. Many made a big point about not using clipless...well, I tried flats, made no difference, went back to clipless. I think that just depends on what you are used to. Many videos make a HUGE emphasis on the pop-up. If you are used to hopping up on little trail features, it's not a huge leap to do this and in my case, because the videos were emphasizing it so greatly, I was going overboard on it, same thing with some saying to be in an easy gear. I found getting a "clean" pop with the pedals in the 2 and 7 o-clock to be critical to learning, where the wheel comes up straight, slightly after that, you rock back and kind of lock your arms, but if it doesn't come up straight, it's damn near impossible to go any further, you just fall to one side. Now I can bring it up sometimes not quite straight, counter-balancing at the same time, but it's still not a good way to start. Point I'm getting at is that there's a lot of people that think they are great at teaching this that have made videos. They each have their own perspective and there are some useful elements, but don't think too far into each of them. It's very hard once you've learned something to put yourself back into the shoes of someone with no concept. I don't think the videos do as well with this as they could.
But keep at it, once it starts to click, it starts to make a lot more sense.