First, educate yourself. There are incredible resources available and you should take some time to really learn more about Human Trafficking prior to getting involved. The SA Counter-Trafficking Resource Library is one starting point with available resources.
Once you know more, consider how you might get involved on a day to day basis as an individual and with regards to your own personal choices, activities and practices: anyone can be an Everyday Abolitionist and conscious consumer.
Lastly, there are many great organisations working against Human Trafficking with whom one can volunteer or work. Be realistic and honest in terms of what you want, need and are able to offer: for example, are you looking to volunteer or intern, or do you require a paid position? How many hours do you have available? How might you use your talents and skills; what you are passionate about, and how you might possibly use that to contribute in some way?