Sewing Tip: When sewing inner corner edges, it helps to transfer the seamline to the fabric so that you know where to pivot the stitch in the sewing process.
You may find yourself sewing inward-facing corner when sewing self-finished corner edges or inner corner seams. In these instances, you will find yourself having to follow the corner seam allowances which can be quite tricky if the seamlines are not directly marked on the fabric. The easiest way to to transfer the corner seamlines is to refer back to your sewing patterns or simply measure the seam allowance width from each edge inward and mark it with tailor's tack or a fabric pencil- this technique is displayed above.
The marked seamline will help you identify the exact point at which to pivot the corner stitch. This seamline serves more as stitching guide providing an exact line to follow as you apply the machine stitch evenly and accurately. If you attempt to stitch a corner seam without these marked seamlines you will be fine until you get to the corner area- at the corner you have to measure the pivot point which can be quite confusing especially for beginners- this is where those transferred line serve a crucial role in facilitating the process.