Pruning fruit crops is critical for the health and productivity of the plant. The goal is multi-fold: to let in sunlight, to increase airflow, to remove diseases and insects, and to reinvigorate the plant. Pruning is not an optional activity. Beginners often are reluctant to cut any part of the plant off — this is a mistake. More harm will be done by leaving too much wood on than removing a little too much. Of course fruit crops differ in their pruning requirements and some are more forgiving of a mistake than others. For highbush blueberries here is some good reading:
For homeowners, check this one out too: http://www.extension.org/pages/29241/pruning-blueberry-bushes
If you are interested in grape pruning here is a great resource: http://www.extension.org/pages/54499/grapes-production-managing-the-vineyard#Pruning
Pruning should ideally be done for most fruit crops in the dormant season, so December, January and February are the months of most activity. In some cases, such as with peaches, pruning can be done at bloom (if time permits). Overall, pruning is a time-consuming endeavor that requires some knowledge of how the plant growth and fruit production. No doubt about it, pruning correctly takes practice, but in just a short time anyone can become proficient at pruning their fruit crop plants.