I can't stress enough, that if you want a professional finish to your sewing projects then you must clip your corners & curves. This will give the seam allowance room to adjust and sit flat. If you don't then it will pucker.
Here are examples for how to sew & clip corners and curves.
For the inward & outward curves, use v-notches and clip close to the seam but be very careful not to clip the stitching. Something so simple will make such as difference.