Self Marketing or Agency?

I am in the process of starting a consultancy business in Occupational Health, Safety, Environmental and Quality Assurance / Compliance in Durban. The consultancy already has registration or affiliation with various institutions in South Africa and International, including Dept. of Labour for First Aid training. My main problem is getting the word out on the street. As far as marketing goes, I have no idea what I am doing but willing to learn. My question would be, do I try and market the business myself, or contract in a agency that will do the marketing for me? If going with a agency would be better, where on earth do I get contact details?