working with commission

Hi,

I have a question here about working with commission. I recently contacted a wedding venue to arrange a weddingand they asked me if I worked on a commission basis. I have never done that so I would like some advice about this topic.

Is it profitable to do this? I mean instead of charging the couple a set fee for their wedding package by letting the venue do all the planning while I get a commission?

Have any of you ever done this?

Regards.