The way I learned was at an intersection where two crowned roads met. Approaching as you normally would in the right lane, slow to a stop and cock the front wheel to the left, with the right pedal forward at approximately 3 o'clock and the left pedal back at 9 o'clock. What you'll be doing is just barely pedaling uphill to the left as you let the bike roll slightly back and downhill; up and back, up and back. Best to be on flat pedals without clips when learning. You'll probably fall once or twice. I later amazed folks in Europe trackstanding on a loaded touring bike. Have fun!

That was on a normal derailleur bike. I later tried a fixie and found it much easier with the ability to actually pedal backwards. Fixies weren't locked to every lamppost back in the '70s.