I am not a makeup artist but I can tell you what business cards I like AND keep
I think that anything else than regular 3.5" x 2" cards is a good idea - people want their cards neat and organized IMO. You could go for rounded corners (one rounded corner with others left square could be nice) or even punched or embossed designs but if I were you I would stick with the standard dimensions.
Colorwise, I would choose either something classy (white, offwhite, cream) or reasonably colorful (nothing too "showy"). I think it depends on your target group of customers (maybe it wouldn't be bad to have two sets of cards - one classy and one more edgy)...
As someone already mentioned, it is nice to have at least some space (for example the other side of the card) for writing additional info, new contacts and so on on the card.
If you would like to have some pictures/photos on your card, please please do not overlay them with text - it is not very nice visually nor technically
I personally think that lineart is more suitable for business cards than any photos or other realistic pictures...
On the idea of CD-like cards... neat idea but unusable in broader perpective - think netbooks (usually do not have any mechanic at all), laptops (have only a kind of "slot" which does not work with irregular CDs) and computers which mechanics do not allow for insertion of these card CDs (in 10 years I had 1 - ONE - computer capable of working with these "nifty" CDs) - including a www address on your business card does a better job, I think
Well that's about all I can recall about my favorite business cards right now, I hope it is at least of some help