*) In gorges (at least in the Austrian ones) get down on your belly and shoot below the bridges. I was doing that for like 15 minutes when a couple passed by, thought I was dead and had to step over me on the narrow bridge.
*) Switch to "Bulb" more often instead of sacrificing image quality for ISO and aperture.
*) Expose looooooog more often. It's crazy how the colors start to shine once you reach really long exposure times. This one had 123 seconds.