Think of it like you are just tightening a screw really. If you turn it clockwise (tighten) you are pushing the screw MORE into the hole....and in essense making the hole smaller (leaner, less fuel allowed to go through). The opposite is also true. If you loosen the screw (counter-clockwise), you are making the hole larger and allowing more fuel to go in (richer).
That's what I've been doing for several years, and suddenly a friend of mine told me that he'd heard and read all over the place it was the opposite. I was like What the.. Turned out I misread him though.
The LSN and the HSN work the same way. JUST like the valve on the side of the house that goes to the garden hose. Open it up...counter clockwise, more water. Close it, clockwise, less water.
The idle screw is opposite. Turn it clockwise, and since it's a mechanical setting, it will PUSH the idle setting to a higher RPM.