There are 5 techniques on pattern making sewing that you can use. The first is drafting from scratch. This is the technique people use if they are new to pattern making. This is the approach of people buying the pattern making a book and then sewing it. The second technique is to tracing existing garments. This is the techniques that use in the fashion industry all the time. In this technique, the pattern creates by tracing around different sections and when the fit is well, and then you develop any styles from basic pattern sewing.
The third technique is to deconstructing the existing item of clothing. This is the method to deconstruct an item of clothing in order to get an accurate pattern from it. The downside of this technique is it will need a lot of time. The 4th method is modifying the well-fitting commercial pattern. This is the approach method for those who learn to make sewing patterns for other people.
The last method is to use draping to create the 2D sewing pattern. This is the other favorite method for pattern making sewing. With this method, you will need the dress stand or human for the model. Which is your most favorite pattern making sewing? It depends on your skills level and creativity.