Observing eclipsing binaries
www.skymaponline.net might be the one you want.

Main goal when taking images in terms of timing and exposition:
1. Choose time with good sky condition (e.g., clear sky, no wind)
2. Expose long enough for good S/N ratio, but not too long that CCD is saturated.
3. If you want to measure the length of the eclipse, you can follow since it is coming in until going out. Or, you can take a couple of images at different epochs, then assume some trajectory and just doing some math.