Wear a brightly coloured t-shirt adorned with a large logo of a well known charity, hang a name badge on a ribbon around your neck and carry a clipboard. Smiling also helps.
Please refer to the diagram linked for a graphical representation. The baseball represents your sphere of impenetrable space.
Turning from left to right (or vice versa) with a hand tentatively raised - as shown by the "ball rotation" in the diagram - will enhance the effect.
The "higher air pressure" depicts pedestrians that dismount the curb, the "lower air pressure", those who look at their watches and speed up.
The "flight path" depicts the pedestrian who pretends to be on the phone - currently the only possible functioning method of force-field penetration known.