Princess Seams give a great fit because they put the shaping right where it is needed and they do so without any excess material. However they can be a little difficult to sew because you are stitching two very different shapes pieces of fabric together. This video and blog tutorial will show you a few simple tricks to getting a nice smooth seam with no puckers or pleats!
Stay stitch the seam of the garment body. The stay stitching is permanent and sits just inside the seam allowance.
Pin the side body piece to the main body piece matching notches, pinning to the bottom edge, and finally pinning the top edge. One piece will seem to be bigger. Divide the excess fabric evenly between the remaining area to be pinned and pin it. Do not clip the body piece at this point.
At the machine, set up the free arm. Begin stitching the seam together sewing slowly and sewing right up to each pin before removing it.
If there is excess fabric that is going to form a fold or pleat, clip the seam allowance of just the main body piece up to but not through the stay stitching. This will open up the main body piece and allow the two pieces to be stitched together without puckers.
Often you will find that not much clipping is needed. I didn't clip the back body at all and only had to clip the front body piece at two points. Press the seam flat and then open, pressing over a pressing ham so you are pressing the shape into the garment.
Here is my finished Rush Hour top with smooth princess seams!