I find heel-toeing on the street is much more difficult. You don't have the brake pedal depressed as far or as hard on the street so you have to reach for the throttle. On the track, the brake pedal is buried in the carpet, it's much easier.
I'd just practice blipping the throttle and downshifting (no brake) since that is the most complicated part. Get that down and then start adding the heel toe part.
2015 F34 328iX GT Glacier Silver
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red