There is no better way to ensure a good fit than to measure yourself and to measure your pattern.
A pattern is geometry.It is a series of measurements mapping the body.
It isn´t personal.
Clothes, and how they fit is subjective. Some people like a tight fit , whilst others prefer a relaxed silhouette.
If you are uncertain about which size you should choose - because it is stretch, or because it is an outer layer, measure a garment you have that is of a similar fabric or cut and use it´s measurements a a guide.
This method is a useful guide in deciding how you may need to alter a pattern to suit your purpose.
Download these tools, they are useful.
Pdf document to record your measurements.
Coming soon ..
How to sew side seam pockets into stretch fabrics.