I wanted to share a few tips on how to get started on your dress from a man's shirt. I know you are going to make one because it is so easy to do. I don't sew anything that is hard - someday I will challenge myself more, but for now it's all about getting it done quickly.
When picking a shirt, the bigger the better. The more fabric you have to work with, the easier it will be to cut out. This will also make it so you have enough fabric in the sleeves of the shirt to make new sleeves for the dress.
Taking off the pocket - if there is one, unpick it off. Gently press the area where the pocket was with steam to minimize the holes that might be left. If they are too large, you can always turn it around and put the buttons on the back.
Cutting up the shirt - go right along the side seam and cut. Go along the seam until you reach the collar. Cut off the collar.
Cutting off the sleeves - cut off the sleeves following the seam as close as possible.
This is what you will have - a front and a back panel to use to cut the dress out of.
Now, with the piece of fabric that has the buttons down the middle, fold in half as close to the middle as possible. Iron in between the buttons. Now, pin it together so that it stays in place while you cut out you pattern piece.
Now, here is my homemade pattern piece based on the Simplicity pattern 5695. I have taken view D and added 4 inches to the bottom of the dress. I eliminated adding the ruffle on the bottom that it calls for as well. I also widened it about 1/2 from the middle of the pattern piece down to the hem. But, other than that, I pretty much follow the directions from the pattern.
One last tip - take the sleeves from the shirt that you cut off earlier and cut along the bottom seam to open them up. There should be enough fabric there to get two sleeves for your new little dress.
Since I follow the pattern for the rest of the directions, I can't really qualify this as a tutorial. If you have any questions, don't hesitate to ask. I will help you as much as I can.