Rachel, why no contact info other than email? An address and/or phone number are customary.

Also a standard business card is 3.5 inches wide by 2 inches deep. It needs to be that size, and to be at least 300 dpi for printing purposes is best.

Take into consideration that you don't want any text too close to the edges of the card, it just would look unprofessional.

Where are you planning on getting it printed? Most copy shops will take a pdf, just a jpg file is too low-resolution ...