My tutorial ... unpicking a seam

Trimming a seam helps achieve neat seams, prevents small creases and fabric bulk at the seam.
In short, it makes for nicer finishes!

Trimming a seam on an inside curve

Make slits, which means cutting notches in the fabric allowance up to the seam line, approximately every 0.5 cm.
Be careful to stop before and not cut through the seam. This will give you a nice curve.

Trimming a seam on an outside curve

Make notches, which means cutting small triangles of fabric along the seam. This will remove bulk from the seam allowances.

Trimming a seam on an inside corner

Make a slit, which means making a cut in the fabric allowance up to the corner. Be careful to stop before and not cut through the seam. If the fabric is thick, cut a small triangle of fabric.

Trimming a seam on an outside corner

Clip the point, which means cutting the tip of the corner diagonally. If the fabric is thick, cut on each side of the corner to further reduce the bulk of the seam.