Will your neckline be round? Or square? Or will your piece have a collar?
There are many different options when it comes to necklines - and often the choice is entirely up to you. In some cases, though, with certain fabrics and with certain finishes, some necklines will be more suitable than others, so before changing your pattern, have a think about how your neckline will be finished (will it have a facing? Will it have a rolled hem? Will it be finished with a bind?) and if the fabric you are using has the stability to support your choice. You also need to consider the location of your fastening or closure (does it have a zip in the centre back? Buttons in the centre front? Does it fit straight over the head?).
Neckline options are never ending (just type "neckline options" into Google and you will get a plethora of images and ideas), but I have picked out a few of the more common ones as examples. When drawing your new neckline on to your pattern it is often good to do it on a full front piece (rather than just on the half) so you can really see what it will look like and make sure it is balanced and smooth.
If you have made a toile of the pattern you can even draw the new neckline directly onto the fabric while it is on a mannequin and then transfer the changes onto your paper pattern.
The round neck is the most common of all necklines and is suitable for all fabrics. With a light fabric such as chiffon or organza consider a hand rolled hem finish, or a bind. If you are using something heavier, consider finishing the neckline with a facing (either a separate neck facing or an all-in-one facing that will also finish armholes). A round neckline is compatible with most closures/fastenings : buttons in the centre front or centre back, a zip, a placket, or an opening at the shoulder.
The scoop neck is a deeper curve than the round neck. It is suitable for use with most fabrics. This neckline is often used for t-shirts and other jersey garments. Finish with a bind, rolled hem or facing. If scoop is deep enough, it may be slipped over the head, otherwise incorporate a centre back opening (buttons, zip or placket).
The boat neck is a wide and subtle curve and can be made with most fabrics. In a lightweight fabric, finish with a rolled hem, or if using something heavier, make a neck facing to support the shape. This neckline is compatible with most closures/fastenings : buttons in the centre front or centre back, a zip, a placket, or an opening at the shoulder.
V-necks are most often seen in t-shirt designs (made from jersey), but can also be incorporated in woven designs. A v-neck can be made with straight lines (dark green line) or a slightly curved line (light green line). A v-neck works best with a centre back opening of some sort (i.e. buttons, zip or placket), or with an opening in the side seam. If the neck is wide enough, the design may be slipped over the head without a fastening. To really highlight and support the v-neck use an all-in-one facing.
For a slightly softer neckline, widen the neckline into a wide v-neck (lower the centre front less than the standard v-neck and reduce the shoulder by more). As this is a more subtle neckline, it can be achieved with most fabrics. Finish with a facing or a bind. This neckline could possibly slip straight over the head, or have a fasting in the centre back seam (buttons, zip or placket).
A square neck will work well with stable woven fabrics - such as heavier cottons and silks or wools. It is best to finish this neckline with an all-in-one facing. You will need a closure in either the centre front or centre back (buttons, zip or placket).
Like the square neck, the round with split neck, is best for sturdier woven fabrics that can support the shape. Finish with a facing. For this neckline you will need a fastening in the centre back (buttons, zip or placket).