Web content itself isn’t enough to make maximum readability. Web design and layout also play their role in optimizing web readability.
Be very careful if you use graphic image as background. If you don’t actually need it, better use plain background. It’s much easier for eye to read text on plain background than the one with graphic image. Not just plain, but plain with enough contrast between background and text.
Choose san serif font for your text. When reading on the monitor screen people feel more comfortable scanning through san serif. If you decide to provide printable version of the page, use serif font for that one. But the main thing is: don’t mix up serif and san serif in one body text.
Don’t serve user with a screen full of side to side text. It will make users eye tired, they have to jump so far from the end of one line to the beginning of the next line. Use narrow column instead. And Don’t use full justification on the paragraph format. Let the left side of the column have different stopping points. It’s easier to read.