What you'll need:
Card stock in several colors
Photos: you can find photos like these at antique stores or download the ones below.
Fun decorative papers in small prints
Small point Sharpie
PS: Here's a time saving idea. Instead of trying to remember everyone's birthday buy yourself a monthly birthday calender and fill it out. Then each month write all your birthday cards on the same day at the beginning of every month. Address them and stamp them. Place the date it's to be mailed near the stamp. And you'll never forget a Birthday again.