This one was by instinct, but then again, when you use film and have to learn to trust yourself, you develop pretty good instincts. Not perfect, but pretty good. ;-)
The first couple of nights in Paris, the Eiffel tower had two revolving spotlights emanating from the top of it. On the second night I set up to catch this and decided to expose for a two or three times as long as I had been, but covered the lens intermittently with my hands. The idea being I wanted to break the slowly rotating beams of light up into more distinct lines rather than them blurring into a halo of sorts. Or at least, that was sort of my thinking. It turned out alright. This time at least.
So, photo tip #2. One of the great advantages to digital is the instant feedback. The ability to experiment and see the results immediately can be extremely helpful. The drawback to that instant feedback is that it is far too easy to rely on that little screen to confirm things for you. You begin to trust the camera to tell you if things are right or not instead of yourself. So my tip tonight is limit how much you use that screen. In fact, unless you are doing something highly experimental, try turning it off and not using it all for long stretches. Go a whole day of shooting without the confirmation the screen brings. Instead, learn to trust your own experience and instincts. You may gasp and say you could never make it a whole day without the reassurance that screen brings you. I would say that is precisely why you should do it. And then gently remind you that I do it all the time with my film cameras. It causes no apprehension in me at all to not see my exposures for days or weeks. But then again, I trust my knowledge and experience to a great degree. So, try it. Go a day. Look at the images when you get home. Realize that by god, you do know how to properly read a meter without the camera confirming it. Then leave your screen off another day. Then a week. Then just get in the habit of leaving it off all the time, turning it on only in those circumstances where the feedback is remarkably handy.
Learn how to trust yourself. And trust me, you can do that. ;-)