I have found the best marinades I have ever used for Venison. They are absolutely fantastic!!! I have ZERO affiliation with this company and no vested interest. I have used them quite a few times with venison and they are the BEST I have ever used, bar none! I even tried the spicy guacamole and it also was fantastic. I got this at the local grocery store in the Hispanic section and it should be easy to find. I have used this for venison fajitas and also for venison al pastor. You will not be disappointed.
http://www.fronterafiesta.com/store/grilling-marinades/49
http://www.fronterafiesta.com/store/grilling-marinades/49