Here's a simple makeover to add some decoration to a plain T. This is pretty self-explanatory, so it'll mostly be a pictorial tutorial (I love saying that).
Make enough bias tape to go around the neck and about 4 inches down the shirt front. Cut the ends into a "V" and press down for a nice finish.
Make the bias tape for one side twice as wide as the other, so they overlap for the button placket.
Cover the raw ends of the bias tape with a square patch, stitched on with an "x"
Bias tape around the neck
Add buttons & buttonholes
Done! And some bad nighttime flash photography to see the final product:
Now go make a cute skirt for a whole coordinating outfit!