I had some great stiff cotton, so I decided to make a blouse with a crisp collar and cuffs. I used a simplified method for cuffs that doesn't require a true placket. This is the same method I use for cuffs on my boy's shirts.
To add cuffs to your simple blouse, lengthen the sleeves to 1 1/2" above your wrist. (If you want a collar also, see instructions here.)
-Two rectangles 5" x 10 1/2" with interfacing (This size will fit a 7" wrist. For a different size cuff just adjust the width.)
-One 14" strip that is 1" wide, pressed into quarters (just like a bias tape.)
Prepare the sleeve for a cuff. Make a mark half way between the edge of the sleeve and the center. On that mark, make a slash 3" long perpendicular to the bottom edge of the sleeve. At the end of that slash, snip a small V.
Fold the cuffs in half with right sides together and stitch the edges.
Clip the corners, turn, and press. For the top edge that is open, press each layer in 1/2".
Stitch the buttonholes. Cuffs are prepared and ready for installation.
Prepare the vent. Spread open the slash so that both edges are making a "straight line." Slip the slashed edge inside the prepared tape. The point of the V should just touch the inside fold of the tape. Stitch straight across.
Fold the vent toward the center. Tack the top and press. You'll be left with a clean simple pleated vent. **Be sure to you make a right side and a left side. It's easy to get mixed up and end up with two of the same side.
Attach the cuffs. You'll just slip the sleeve inside the opening of the cuff and top stitch across. Depending on the opening of the sleeve, you may need to add pleats or gathers for the cuff to fit. I like to have two small pleats on my sleeves. Pleats should go in the same direction as the vent. Stitch on your buttons.