How to Build a Low-tech Website by Low-tech Magazine
How Wikimedia helped mobile web readers save on data by Wikimedia Foundation

1. Use static images
2. Reduce animation
3. Dithering images
4. Use default typeface
5. No use of third-party tracking, advertising and cookies services
6. Use alttext for images
7. Use javascript only when required (use noscript tag)
8. Use high-res images only when required
9. Use black-and-white images
10. Rely more on CSS over images for visuals
11. Use svgs