I started out selling at craft shows last year, and the first one I did I hauled everything I had to the show. Then after, I hauled most of it back again, lol. I think it's difficult to say what to bring because you kind of learn as you go. One thing I learned is not to have the table look too busy or it is overwhelming to people. What I do now is bring a shoe box sized container of each scent I plan to sell and only put out enough for one row on my display shelf, about 4-6 bars can fit in a row. I have 2 shelves that can hold about 5-6 rows a piece. It looks neat and tidy, and customers can easily peruse the different soaps I have. When I need to restock I just get the extras from the boxes.
I am also learning what types of things sell well for me and what doesn't. I had a few people ask for sugar scrub squares around Christmas, and I didn't have any. So I made some and then they didn't sell. I just gave some of them away and threw away others that had discolored. I am still in the process of learning not to jump in and make EVERYTHING that is requested (or that I read about online) or I end up with a lot of stock I don't use.
Popular scents will differ from venue to venue as well. I think it probably takes a while of getting experience under your belt before you can truly look at numbers and what products and scents to bring. It can be frustrating but the whole process to me is kind of fun.
In the beginning I also used my co-workers as testers. They call me the soap dealer now because I got them hooked with free samples in the beginning, in return for their input on the products, scents, packaging, etc, and now most of them keep coming back for more, they're my best customers.