How do I use the stalker detector effectively and wisely?  

PUT DISTANCE between the samples you take.  Hitting the 'Detect Stalkers' button in green takes a sample for 60 seconds, recording all of the devices your own device is able to detect in proximity.

Put your sneakers to the asphalt and MOVE AWAY from where you took the first sample.  Why? Because it remains apparent that if you move and someone is actually following you, THEN THEY WILL NEED TO MOVE WITH YOU otherwise they are NOT stalking or following you.  UNDERSTAND THIS.  

Another purpose served by your putting DISTANCE between where you take samples -- it allows my app to cleverly eliminate the stationary devices and narrow down the list to cut to the chase by eliminating things that don't move like wifi access points, devices that are not moveable.  Leaving you with less noise, more strong suspects...

Click on a device to reveal a button that will add that device to the radar feature of Lookout 5o -- allowing you to get a heads up whenever that device and its owner are nearby.