I know this is too late for the person who originally asked, but in case someone else needs help I thought I'd add my .02 cents.
Along with what everyone else has said, I think anything nature-like is a good start. I am including a picture of a card I recently made for my brother-in-law to give you an idea. This card would be good for a woman or a man. Just change out the greeting, and this card would be suitable for birthdays, graduation, sympathy, thank you, etc.