Recently I was working on a Drupal website and needed to add a new feature: to upload and display PDF files in the browser. As I browsed the options on drupal.org, I realized I would need to choose from several modules and decide on the most appropriate one for the job. Here is an account of my decision making process.
1. The first step is to perform needs analysis. In other words, I needed to define what I wanted. Do I want to have fancy page-turning feature that some third-party vendors supply? Not at this time.
2. My website is built with Drupal 7 so I need to have a Drupal 7 version. I also want to follow the general guidelines for choosing a Drupal module. Bascially, I want to choose a module that has several thousand downloads. This will ensure that it is stable and widely used and being actively supported with current bug fixes and security fixes. I try to avoid contributed modules that have a licensing fee.