I'm so sorry, I'm late, very late...but I made a long break. I use organza! The sleeves was the difficult part of the dress for me. Ehm, longer interessted in an explanation? Then I would give it a try^^
All I wanted was puffy!^^ I cut strapless sleeves out of the dress-fabric. Bevore I sewed them together, I ruffled the organza in several layers and sewed it on the upper side of the sleeves. Like a pleated skirt, you know? For example: [link] (I hope, it's okay to show that on DA O__o°)
It's really difficult to explain it without pictures. I worked a long time on the damn sleeves! I hope, it help a little bit.