the different levels of reading and keeping up with the output previously.
What do you do after you finish reading a paper? Do you simply throw the article on a pile on your desk? Do you take any action at all?
In my opinion, archiving a paper is as important as reading it. Nothing is as annoying as when you realize you read something interesting, but can't remember the author nor title. And that's exactly the pitfall you want to avoid if you keep up with the output.
By investing just a few minutes of time after reading a paper, you can archive your articles and find these back when necessary. Here's a few things to consider:
1. Electronic archive
If you undertake a research project that spans multiple years, you will need referencing software. I use Endnote, and I archive all papers I have read into my PhDBibliography library. At the university network, I use ISI Web of Knowledge to look up the paper I read, and most of the times I can simply download the information (full reference, abstract, keywords, times cited,...) into Endnote. I then add the .pdf version of the paper to the reference, to make sure I can always find the reference back.
2. Paper archive
In this regard, I'm totally old-fashioned: I still print everything I read (some day, I'll switch to a tablet reader). I don't want to toss the paper that I read into the thrash, also because most of the time I sketch and comment in the sideline. Therefore, I archive all hard copies of articles. As I described here, I have everything in alphabetical order for the first author. When I'm not sure who wrote the paper I'm after, I can still search in my Endnote library on the keyword or date.
3. Notes on paper
Besides sketching and commenting in the sideline, I also note down a few keywords or a short summary on the first page of the paper. This method not only helps me to summarize what I just read, but it also helps to bring back the topic if I revisit the article.
4. Notes and tags
In Endnote, I try to add keywords or some additional comments such that I can make a search for a keyword and have all relevant articles showing up. A search for "sustainability" or "compression strut" for example can be very helpful when I prepare a paper and need to write the introduction and literature review by referring to the relevant papers on that topic.