I found my TA through a friend. She had used her to book her trip for a friend's wedding and said she was pleasant to work for. We met for an inital consulation and at that point I already knew where I wanted to do my wedding. When we sent out our save the dates, we put our TA's information on there and asked everyone to contact her directly. She has already taken everyone's deposits and will be following up with everyone for full payment. It makes it much easier on me that I do not have to worry about any of these things. She is also keeping lists of people that are attending my wedding, but not travelling on the same flight (they are from different cities/countries).
Also, I lucked out and she is going to my resort in November. So I'm going ask her to meet with my WC and take some photos of certain things for me - since I didnt get a chance to do a site visit.
It depends on how big your wedding is and how many guests you will have. If you numbers are quite large - I would hire a TA to deal with all the travel arrangements for you. It takes a load off of you!
Hope that helps