I am new to my field (cell biology / immunology) and I would like to ask about the best practice to annotate or summarize research articles and reviews for long-term retrieval. When I start reading into a new topic, I end up highlighting almost each paragraph of the paper/review. This doesn't make any sense, and it is actually making me slow and frustrated and it is holding me from reading more. Could you please share your thoughts.
Update: although two very important points of how to approach new papers and how to tag them have been addressed in the answers so far, my main concern was about the new acquired details which I can't remember a few months later. For example, I read a paper about JAK/STAT signaling two months ago, now I can't remember for example which JAK attaches to which cytokine receptor and interacts with which STAT. I need to skim through the paper again to find this piece of information. So, what I am looking for is an approach to accumulate the new knowledge and to facilitate reviewing them without the need to skim through the paper again and again. I know this will come with experience, but at the beginning there are too many new facts to keep track of.
My current approach consists of two parts.
First, I make use of a Reference Management Software (in my case Papers), which allows me to highlight/annotate PDFs and to write notes for each PDF. It's easy to do a search which covers all the notes that I write, and even the internal text of the PDF. PDFs may be tagged or assigned to multiple categories/subfolders; they can also be exported with or without annotations.
Some examples of Reference Management Software (of which I have experience with 1-4):
Second, I write a summary in a review article for each major topic that I am looking into seriously. I previously used Microsoft Word to do this, but have since switched to LaTeX/bibtex due to the convenience of being able to handle hundreds of references (or equations). The usefulness of a review article format is that it is easy to convert into a manuscript (keeping equations, references intact) when the time comes to write a journal paper. Furthermore, should I need to revisit a research area that I have not touched for many years, a review article allows me to quickly refresh my memory. Having all the relevant references in a single place also helps. A side benefit is that I sometimes send my review articles to collaborators to help them get up to speed.