Over the past six months, I've published a series of articles about textiles. I believe textile choice is at the heart of ethical fashion because it has such a huge impact on the lifecycle of an item. Textile design can affect wear, durability, water use, environmental impact, comfort, among other factors.
I encourage you to read up on the various textiles designers use and learn about the issues surrounding their use. Armed with this knowledge, you will feel more informed to make textile choices based on your own ethics.