What do you think is the most effective way to promote Safety in the workplace?

First of all the management needs to be committed towards safety.Get a thorough hazard identification & risk analysis done for the scope of your work , define the required control & make frequent assessments to see the level of implementation & effectiveness . Go in for OHSAS 18001:2007 & follow the standard.It will defenitely contribute towards safety adherence & enhancements.