I totally agree with the acronyms. Being a new member on a project is hard enough, but acronyms should be defined early in the document.

A few additions if I may:

1. Bullets/numbered lists better than paragraphs. More visual this way.
2. Embed screen shots within documentation. This usually comes up for me because my company documents on a wiki (which leads to point 3). I don’t want to have to read something and then scroll up to open an attachment. Although, sometimes attachments are necessary.
3. Wiki is a nice publishing tool because it’s searchable. My company’s even indexes attached files so if you search “test” that key word gets returns matches in the wiki text or attached file text. I agree with TOC and index in Word doc, but searchability is even better.
4. Embedded hyperlinks to other topics to jump around document is also useful to quickly understand a concept presented previously or later in the document.

I hope these help.

One thing I’d add is: when words and still pictures won’t do, make a video tutorial (also known as a screencast). It can actually be faster and smoother to create a quick one than labor over how to explain it with more static media.

A growing number of websites (and I’m a visual guy too) are using vidtuts to both attract people to use their products or services, and teach them new skills to help them get more value out of their experiences.

Take care!