According to Wikipedia, readability is defined as reading ease, especially as it results from a writing style. Only experience, practice, and hard work can improve a person’s writing style. Let’s increase readability in a different manner: with typography.
The web is awash with examples of terrible typography: poor font choice, minuscule text, horrible colours. Everyone has came across a web page that was just about impossible to read. There is a solution. Readability by Arc90.
I discovered this tool shortly after my ophthalmologist explained that extended computer use strains eye muscles and that larger fonts may help. Since then, I use it to read almost every article I come across. The Firefox add-on makes the process even easier. After landing on the next great blog post from Hacker News, my next action is invariably to enable Readability with CTRL ALT R.
Give it a try, and give your eyes a break!