Just like everyone else I read as much as I could about the techniques online, then from there its all about getting out and trying, having close calls and scaring the ***** out of yourself....No matter how much you read or how much instruction you get in real life, it still all comes down to just getting on the bike and trying things...Knowing the technique is important, but 99% of the time when you get there all that stuff you think you learned reading goes out the window and you remember them as your sliding down the asphalt on your ***. Then you get the classic "but but but I was on the rear brake the whole time" when in reality as soon as the bike reached balance or past it their feet came off the pegs completely....
Best bet it to go to a parking lot or deserted street and practice, wear gear, and always try to have at least one other person with you in case you get hurt and need help. If they can film you, its nice too because after the fact you can watch the video and realize what you think is 12 oclock is actually only your front wheel lifting 12 inches off the ground
Good luck for some it comes easier then others, take your time and dont get too exited. A lot of times I see newbies, they try 50 times and then finally they get a good one, then that pumps them up so much the next one they try too hard and crash...