Nowadays things are different. I rarely look for my sources in the library if I'm not doing a particularly important research. I generally try to find what I need in the Internet.
The first thing I do is typing one or some key words in a search engine and then I start skimming over the first proposals it gives me. It's definitely not an easy pass; there are often plenty of results. After that, I generally read or take a look at the passages under the URLS which contain the terms I'm looking for. If I think a website could be useful or interesting I click on its URL ( and if I recognize the website address as belonging to an important magazine, a reliable organization or if I know the author, yes, all these things would be further guarantees for me).
Most of the times, I understand what type of website I'm dealing with, just looking at its layout and at how information is presented. I chose the websites in which the presentation of the topic I'm interested in is particularly detailed and preferably enriched by some useful links. In this way I can always find more information if I need and obtain further material for possible connected examinations.
However, I admit I look for the date in which the site has been last updated in few occasions; if I like it, I generally pay attention just to the contents.