I would say experience, is what makes a great wedding DJ experience is a plus. You have such a wide variety of people at every wedding so you have to now how to entertain all ages. Also you need to know when to let loose and when to stick to the script and just do what your supposed to do. Verses later on in the evening when everyone is dancing and having fun that is when you start focusing on getting people on the dance floor.
If you have not failed a hundred times to get where you are at you are not going to know what it feels like when you do fail that first time.
I have reviews online you name it, you can go read these reviews and these are all clients you can reach out to in real life. I have faith in my work but I want the client to have faith in my work.