I've found that even if it's too light to use a long exposure via "bulb," (ie evening, urban area, etc...) just bring the ISO down, close the aperture a bit more, and set it anywhere between a 1-30 second exposure. Then you point it where the lightning is most frequent and, if possible, lock your remote into continuous shooting mode (mine has a slide-over catch over the shutter release). As light conditions diminish, decrease your shutter speed until its max (30 seconds on mine) before you start cranking your aperture open.
Also, some other tips:
If the lightning is in the rain, forget it. Not only do you not want to expose your equipment to the elements, but each raindrop reflects the light from the bolt, flooding the picture and making a great white blob.
Stay close to shelter. 4 times at last count I've just gotten under shelter or in my car before my surroundings got dramatically bright and loud in the same instant. Once I actually saw it strike the light pole 5 feet from my car before I'd even gotten the door shut. If you feel goosebumps rising up, hair standing up on your arms, or a tickling on your neck, RUN. Lightning is about to strike very close.
One technique that I use that can be critiqued and argued freely: I'll usually use my wide lens, cranked all the way out to 18mm. The way I figure it: The more area covered in the shot, the better my chance of capturing a strike. Shooting with 10mp, cropping isn't an issue as long as it's not much bigger than for an 8x10 or smaller poster. With a 20mp, it would be even better!
Last bit of advice: Find either a heavier tripod or something to put on its legs for weight. I've had many an outflow boundary (strong gusty winds just ahead of the main storm) shake my light tripod, screwing up the shot.
So remember, stay outside of the storm and shoot into it (best chance for capturing dry lightning), stay close to shelter because lightning really hurts (you don't want to visit the Lightning Strike Survivors convention in Pigeon Forge, TN every year), and don't do anything stupid (trespass, stop in the middle of the road, move too far from your car into a field, etc... all things I've done) to try and get the good shot. You can't share the fruits of your efforts if you're dead!