when i say taking lens, i mean on the camera ( sorry for the lingo ! )
what camera are you planning to do the soft-shots with ? LF or MF or 35mm ?
you might use front focus and have your lens not open all the way
but stopped down a little bit and focus on something infront of your subject
and use the lens' natural ability to soften your subject. it isn't really that hard ...
you could also shoot with something obstructing your lens and that can soften your subject too.
when i say obstructing, i mean like a finger or something physically close to and infront of your lens
when you expose your film ( or whatever ). try exposing everything with deep DOF but at very slow shutter speeds too
( 1/2 S ) long exposures have a way of softening things up too.