Ways to finish a neckline

Facing

Simple to sew, add structure and it is easy to make a facing look good. On a woven fabric a facing is needed because you can’t make an easy hem on the curved neckline. A facing mimics the neckline curve and you sew the facing to the neckline, right sides together, so the stitch line is the neck edge. If you create a new neckline, you can also create a new facing that follows the same shape. You usually create the facing from the main fabric and may add interfacing for more structure – I rarely do this. I also don’t usually stay stitch the neck line – but you really should especially if you are prone to manhandling your fabric!

First stitch and finish your shoulder seams, then close the shoulder seams of your facing as well. I generally do not add interfacing but if you do add this before joining the front and back facing together. Then grade those seams and finish the outer edge of the facing (pinking shears will do here). 

Then line up the seams of the facing and of the garment, right sides together, pin. Pin any notches and then ease in the rest and pin. The shapes should fit perfectly so if you are having to stretch you may have them back and front lined up wrong. Sew together at the neckline. 

I nowadays grade my seams (I halve the facing seam), press the seam allowances towards the facing and then understitch the facing to the seam allowances. Then I turn the facing, press, and pin, making sure there are no folds or lumps. Topstitch. I quite like a proper topstitch an inch or so away from the neckline. You could hand stitch the facing with an invisible hem stitch if you don’t want to see a top stitch line. 

Using bias tape

Using bias tape is like using a mini facing, bias tape shapes nicely around curves. But it is easy to stretch the tape too much and make it look meh and closing the tape in a circle is a little tricky. I rarely use it. But there are plenty of videos showing you how to use bias tape so feel free to experiment as you may LOVE it.