As previously discussed, your first step should be to visit countries where you wish to import from. While you are there, compile a potential list of trade partners from published trade directories and then contact them upfront to sound them out about doing business with you. If necessary, you can use a research organisation to do this for you as it can take quite a bit of time.
Be aware that South Africa has different trading relationships with different countries and these will affect how you do business with your supplier. To find out more on your specific country of interest, contact the Department of Trade and Industry or visit Seda.