This is an informative blogpost from FotoBridge about how to sort, label and pack your slides for shipping. If your slides are already organized or labeled, it would certainly make sense to send that labeling along with your order. FotoBridge will then label your digital files accordingly.
The slides I sent were in separate groups according to decade, but if I had known FotoBridge would provide this level of organization, I would have included a bit more description to each group. Read this blogpost for more detail and don't forget that FotoBridge is offering readers of The Scrappy Genealogist a ten percent discount. Just use the code "scrappy10" when you place your order.