Activity for Katie

I go for my alterations appointment on Sunday. Till this point I had just planned on wearing no bra, seeing as my dress is strapless. My question is, is it best to wear a bra and shape wear or does it matter?

I bought my dress at DB and I have to have alterations done. I need the hem taken up and and I need the dress taken in. Does anyone know about the amount that DB charges to do alterations and if it'd be best to go there or a local seamstress.