Personally, I look for the MVP usage example - something equivalent to a "hello world". If that's provided by the docs, excellent, that's what I read first. Once I understand the gist of things, I can drill down into more specific documentation.

However, a lot of "documentation" is just a list of descriptions for each function in a library (for example). This is great once you're up to speed, but it makes it hard to get an overall impression of how it works and how to use it. In these cases, I tend to find myself reading somebody's blog post for my initial introduction.