It's pretty much trial and error as you don't know in advance what the intensity or distance to the strike will be. I think you are on the right track with a long exposure to increase the odds of having a strike occur while the shutter is open. A smaller aperture may have helped for this shot (hindsight) but this looks kinda close (inverse square law for the intensity.)
Another trick to try is to use a bulb setting with a remote and place a piece of black card over the lens to stop the exposure after a strike has been recorded.
I would clone out the water drops on the window because it looks like you are afraid to got out in the storm.