With color negative films, contrast is not the problem for a digital cameras. You’ll be able to fit the histogram. Underexposing is not a good idea as @FatihAyoglu explains above.
I’ve found that I can bracket between 0 EV and +2 EV with most of my negatives and that the shot in the middle of the series yields the best conversions.
HDR composites have not given me an advantage that outweighs the effort. It’s certainly okay to see what you’ll find though.
Check this out for best practices, it might help you find your way more easily: