I'm a year into my English PhD, and I've found that the EndNote software is an excellent way of keeping track of articles and anything important I need to keep.

EndNote is a really easy-to-use piece of software which acts as a virtual catalogue for your papers. You can list each item as a journal article/book/book section etc and then add any info (including any notes you've made while reading it) in the same entry. I then file the paper copy in an alphabetical file system. When I want to find, the search functions allow you to search by author, title, word etc, which makes it very easy to find. You can also add keywords to each item, such as "Chapter Two" or "Teaching Material" etc which is helpful when doing chapter revisions etc. Apart from being super organised, it appeals to my inner (or not so inner, at times) librarian tendencies, which are becoming v. apparent with new label maker etc!

I know this is a harder system to integrate if you've already started accumulating and filing, but I'd highly recommend it if you're just starting out. I feel very secure knowing that I can generally find what I'm looking for with one search!

This is my first post to this site - I'm loving it! Apologies if EndNote has been mentioned before, but it's worth a second mention :)