Reading an academic paper is rather like watching an episode of a soap opera, unless you have been watching for a while you will have little idea of the roles played by the actors and the background to what is happening. A book is like a film in that it has a beginning-middle-end and what you need to know is explained.
Sitting next to somebody who has been watching for a while is a good way of quickly getting up to speed, but what do you do if no such person is available or ignores your questions?
How do you find out whether you are watching a humdrum episode or a major pivotal moment? Typing the paper’s title into Google, in quotes, can provide a useful clue; the third line of the first result returned will contain something like ’Cited by 219′ (probably a much lower number, with no ‘Cite by’ meaning ‘Cite by 0′). The number is a count of the other papers that cite the one searched on. Over 50% of papers are never cited and very recently published papers are too new to have any citations; a very few old papers accumulate thousands of citations.
Clicking on the ‘Cited by’ link will take you to Google Scholar and the list of later episodes involving the one you are interested in. Who are the authors of these later episodes (the names appear in the search results)? Have they all been written by the author of the original paper, i.e., somebody wandering down the street mumbling to himself? What are the citation counts of these papers? Perhaps the mumbler did something important in a later episode that attracted lots of attention, but for some reason you are looking at an earlier episode leading up to pivotal moment.
Don’t be put off by a low citation count. Useful work is not always fashionable and authors tend to cite what everybody else cites.
How do you find out about the back story? Papers are supposed to contain a summary of the back story of the work leading up to the current work, along with a summary of all related work. Page length restrictions (conferences invariably place a limit on the maximum length of a paper, e.g., 8 or 10 pages) mean that these summaries tend to be somewhat brief. The back story+related work summaries will cite earlier episodes, which you will then have to watch to find out a bit more about what is going on; yes, you guessed it, there is a rinse repeat cycle tracing episodes further and further back. If you are lucky you will find a survey article, which summarizes what is known based on everything that has been published up to a given point in time (in active fields surveys are published around every 10 years, with longer gaps in less active fields), or you will find the authors PhD thesis (this is likely to happen for papers published a few years after the PhD; a thesis is supposed to have a film-like quality to it and some do get published as books).
A couple of points about those citations you are tracing. Some contain typos (Google failing to return any matches for a quoted title is a big clue), some cite the wrong paper (invariable a cut-and-paste error by the author), some citations are only there to keep a referee happy (the anonymous people chosen to review a paper to decide whether it is worth publishing have been known to suggest their own work, or that of a friend be cited), some citations are only listed because everybody else cites them, and the cited work says the opposite of what everybody claims it says (don’t assume that just because somebody cites a paper that they have actually read it; the waterfall paper is the classic example of this).
After a week or two you should be up to speed on what is happening on the soap you are following.