I recently finished some blouses for myself. I use a basic pattern, but normally, I add pleats.
Here is a basic blouse I made, stretching it out of scraps, which is why I didn't add pleats...there wasn't enough fabric!
The next blouse is an example of what I do if I haven't enough material to put in the 1/2" pleats I normally make: just make 1/4" pleats! (I have three on each side of the placket here.)
And, finally, here is a "normal" blouse, featuring three 1/2" pleats on either side of the placket.
I also had to add a seam in the center back of the blouse, which is normally cut on the fold. Adding the seam in the back enabled me to squeeze the blouse out of the scraps, and it is not noticeable in either blouse.