The specifics of how to prewash your fabric will depend on the fiber content, but a good general rule of thumb is to prewash the fabric.
For more delicate fabrics like silk and wool, use a gentle soap meant for handwashing or baby shampoo.
For woven fabrics, you can pink the edges of the fabric using pinking shears or a pinking blade for your rotary cutter, or you can serge the edges.
Danielle is a DIY/craft/sewing blogger on DIYDanielle.com. She loves to write about projects that she makes for her small farm, her children, and her home.