A lot of photographers have received offers from prospective clients to do work for free - advertising, editorial, portrait, wedding, etc...at some stage of the game every shooter has been told that they will be permitted do the job for no pay. One of the favourite arguments put forward to promote this is that it will be good for the photographer's career. Exposure. Bright lights. Big name. Network connections...
If you want exposure, open up your aperture or slow your shutter speed. There are controls built on most cameras to do this - they are generally on the top of the camera body and do not connect to your wallet. If your wallet opens up, it because someone's fingers are in there...
Bright lights are available from us. We sell Profoto, Elinchrom, Nikon, Canon, Metz, and Jinbei. Come in and try them. We charge money, so you'd be better off to get the client who wanted the freebie to actually pay you and then you can spend it here. That's what money is for.
Big name? Freiherr Manfred von Richthofen had a big name and so did Feld Marschal Erich von Ludendorff....lousy photographers the pair of them.
Network connections? Get a laptop and post selfies on Facebook. Or go down to Fremantle and buy a herring net. You'll get a network and more dinner than you would have from the photographic assignment - if you can find a bottle of tartare sauce you have it made.
You need not feel sad that the client will suffer from not having you do it for free. They will move on to the next final-year student and make the same proposition. Eventually they will find a volunteer.
Note: Brides generally only try to steam you for one wedding and the devil only damns you once, but art directors will try it time after time.