From my experience, straight social media advertisement - from a company twitter / Facebook accout - doesn't generate many candidates.
Using your own network, and the network of the people who work with you, on the other hand works well. What you need to do is request your team to share the roles widely within their network, or even better: directly to the people they think would be best at the role. This always returned the best quality candidates for me.
As an internal recruiter, networking (events, friends) would then be my second port of call.
Third is LinkedIn, searching people via skills and reaching out to the candidates I thought were best suited for the role.
Ultimately, hiring someone is building a personal relationship with them, and that works best person to person. Showing that you are hiring and growing on social media is great for the company's exposure, yet not necessarily to attract people. I use my social media channels to increase awareness, yet I always do hiring person to person.