Things you need:
- a big, button-down shirt
- 4 or 5 buttons
- needle and thread
- straight pins
- someone to help you, or a dress form
Step 1: Choosing a Shirt
Also, try and find a shirt that has darts in the middle of the back. If the darts are at the shoulders, it won't fit as well. It seems like women's shirts mostly have darts in the middle, and men's shirts have darts at the shoulders.
I used a blue polka-dot shirt for my first dress, and a red plaid one for the second. A Hawaiian shirt could also be a lot of fun.