When spraying indoors, where should I spray for effectiveness (baseboards, under sinks etc) and do I use spread or pin spray applications?

Yes, baseboards, under sinks, around doors and windows, behind fridge, washer, dryer. I would use a pin spray for the areas you want to directly target and then otherwise, I use the spray application for more coverage.  I have also sprayed this on my carpets for flea prevention (after making sure it would not affect the integrity of the color of my carpet).