Itís always best to first consider engineering solutions to eliminate or minimize manual handling of materials. Many injuries result from not using handling aids. People should be educated and informed about what devices are available, their safe use, and what should be used in various situations to "take the work out of work" and make it safer.
Split the load into smaller parts, when you can, to achieve manageable lifting weight. Sometimes loads can also be made easier to grasp. Suppliers may be able to help with load size and packaging.
When possible, itís best to avoid lifts from below the knees or above the shoulders. Sometimes mechanical handling aids can be used to avoid this. And sometimes you can position yourself so that the object to move is within a more acceptable lifting range (between the shoulders and knees).
Reference - OSHA Technical Manual1 - Back Disorders and Injuries http://www.osha.gov/dts/osta/otm/otm_vii/otm_vii_1.html
1Non-MSHA links are not meant to imply enforceability by MSHA. They are for informational and educational purposes only.