When you are shooting film, specifically black and white, you want to expose for the shadows (that is, get a direct meter reading of the darkest area of the image (zone 0) and set exposure accordingly) and develop for the highlights (N-1 processing- shorten developer time or dilute the developer). This will ensure you have all tonal values present in the final image.
All things considered, it is better to overexpose negative film (black and white or color) and to underexpose color reversal film and digital images (slide film and 0’s and 1’s).
If none of this makes sense to you, learn the Zone System and thank Ansel Adams for his research.
Push It A Stop 