This is a good starting point for understanding the range of issues facing organisations, particularly if you are new to the subject.
SSN's tips for users
Familiarise yourself with the landscape of health and safety at work and the cultures that makes businesses inherently safe (and those that don't).
Further research may lead you to consider professional advice (of which there is an enormous amount). Use the Sheffield Sustainability Network Forum on LinkedIn to find what other, similar organisations have done and share experiences of consultants and experts.
