Well if you are looking for a slow motion look you actually want to "overcrank" the frame rate (higher framerates instead of lower ones) if you shot something at 12 fps and played it back at 24 frames per second it would play back really fast. If you overcrank at 48 frames per second and play back at 24 frames per second you are playing something in slow motion (you are playing back at half the frame rate that you shot). As for the blurry look, that will come from shutter speeds that are usually 360 degrees or below.
In other words, if you shot a film at a regular (180 degree) shutter speed (24 fps + 1/48 second shutter = 180 degrees) you would get no blur. If you shot at 24 fps at 1/24 shutter (360 degrees) you now have an open shutter. It's a little blurry at 1/24, the lower you go from there the more blurry you get.
So if you want slower motion shoot at a higher framerate (48 fps perhaps) if you want a blurry look shoot with an open shutter or below (have your shutter match your framerate (48 fps + 1/48 shutter = 360 degrees)).