You will need:
Shirt that fits well (not baggy, but not tight)
Try the shirt on and mark a line where you'd like the scoop neck to stop. Now lay the shirt flat and draw a scoop neckline with your chalk (I put my shirt on my dress form Veronica and did this step). You can make the scoop neckline as deep or shallow as you like. I made mine deeper so that I could cut out some of the wording on the shirt.
Flip the shirt over to the back (or swivel your dress form) and find the center of the back of the shirt. Find the marks from the front (where you started your scoop neck lines) and mark a deep "V" in the back of the shirt with your chalk. Make sure you connect the back lines to the front lines at the shoulder seams. I made the point of the "V" sit right above my bra strap.
Cut along the line that you marked for the scoop neck.
Flip the shirt over to the back and cut along the line that you marked for the deep "V".
From the armpit seam measure over one inch. Draw a diagonal line across the sleeve. This shortens the sleeves making them look sort of like a cap sleeve. Repeat this step on the other sleeve.
Cut the ends of the sleeves off.
Finish the edges of the neckline and the deep "V" of the shirt. I used a serger. If don't have a serger you can use the zig zag stitch on your sewing machine.
Turn the shirt inside out and fold back 1/4 inch of the neckline and deep "V". Pin.
Hem the neckline by stitching down the fabric you folded back and pinned.
Find the point of the "V" and line up the edges of the "V" opening (like you're going to stitch the back closed again). Measure 1/2 inch up from the point and mark with chalk. Pin.
Stitch from the chalk mark to the point of the "V". This will create a nice pleat in the back of the shirt and helps to enhance the point of the "V".
Lay the sleeve of the shirt flat on the table. Find the center top of the sleeve by finding the shoulder seam of the shirt. Mark a line down the center top of the sleeve. Then measure 1/4 inch in from the edge of the sleeve, and measure 4 inches out from the center line on each side of the line.
With the longest stitch on your machine stitch along the line you drew. Don't lock stitch!
Gather the sleeve with the stitching you just completed. This will give the sleeves a cap/puff sleeve effect. When you think you've gathered the sleeve enough, stitch over the top of the gathering with a regular, short stitch to lock the gathering in place.
On the back of the shirt, find the shoulder seams and measure down 2 inches. Mark with chalk.
Grab your tie. Measure and cut an 11 inch strip from the skinny end of the tie.
Pin the strap to the inside of the shirt at the marks you made. Stitch the strap to the shirt.
Make a fabric bow and pin the bow to the center of the strap. Stitch the bow to the strap. I also added some felt heart appliques to the front of my shirt to cover the wording on the shirt. For help with applique, check out Max California's applique tutorial.
Now you're done! Go hit up your closet and refashion some shirts! You know you want to.