Foundations of Design and Typography by Christine Castigliano a site which is well worth exploring for no matter what the medium – including textile practice – design principles can be applied.
There are a great many people today who practice design – and call themselves “web designers” – without training in design. Many know their way around PhotoShop and other software, but do not understand the basic principles of design. Naive business owners may pay them, but so much of their work is simply not effective. Don’t contribute to the noise! Learn to avoid their common pitfalls.