Wing chun is a great self defense system if trained realistically, and sparring is a fundamental part of that training. Even as a wing chun practitioner, I recommend beginning with basic boxing style sparring first. You can see a video with the simple boxing progression I teach here.
There are a few reasons I feel this is a good way to start: First, most people punch like boxers, not like wing chun practitioners. So beginning your sparring with boxing will ensure you and your partners are able to use your wing chun against the most common types of attacks. Second, as I detail in the video above, basic boxing techniques will close some of the openings left in wing chun. While I do find wing chun to be more ideal than boxing for self defense, boxing defense adds a kind of 'back up defense' in case the jamming style traps of wing chun fail. And finally, the footwork and movement in boxing is also more realistic than what's taught in most wing chun schools, which will give you a more functional base from the start.