What are causes of dry hair, other than shampooing and using dryer too often?

That's about it. Most dry hair is caused by over-shampooing and over-blow drying, no matter what you've read. Shampoo less frequently, perhaps only once or twice a week; add a conditioner; avoid blow drying and harsh styling products. That will work 99% of the time. If it doesn't, see your doctor to rule out an underlying cause.