Title. This should say as much as possible about the content of the paper, in as few words as possible.
Abstract. This is a brief (usually one paragraph) summary of the whole paper, including the problem, the method for solving it (when not obvious), the results, and the conclusions suggested or drawn. Do not write the abstract as a hasty afterthought. Look at it as a real exercise in cramming the most information in one paragraph. The reader should not have to read any of the rest of the paper in order to understand the abstract fully. Its purpose is to allow the reader to decide whether to read the paper or not. A reader who does not want to read the paper should be able to read the abstract instead. When you write an abstract, remember Strunk & White's admonition, ``Omit needless words.''
Introduction. Tell the reader what the problem is, what question you will try to answer, and why it is important. It might be important for practical reasons or for theoretical (or methodological) reasons having to do with the development of a scholarly discipline. Don't neglect either type of reason.
If the problem is a very basic one, you may state the problem first and then review what has already been found out about it. If the problem is one that grows out of past literature, review the history of how it arose. But do not forget to mention the basic issues behind the research tradition in question, the practical or theoretical concerns that inspired it. (Sometimes there don't seem to be any. In this case, you have probably chosen the wrong topic.)
Your literature review should be appropriate to the kind of paper you are writing. If it is a thesis, you should strive for completeness, both in reviewing all the relevant literature and in making the main arguments clear to a reader who is unfamiliar with that literature. For a course paper or journal article, it is sufficient to review the main papers that are directly relevant. Again, you should assume that your reader has not read them, but you need not go into detail. You should review only those points that are relevant to the arguments you will make. Do not say that ``X found Y'' or ``demonstrated'' if X's conclusions don't follow from X's results. You can use words like ``X claimed to show that Y'' or ``suggested that'' when you are not sure. If you see a flaw, you can add, ``However ...''. Try to avoid expressions like ``Unfortunately, Smith and Jones neglected to examine [precisely what you are examining].'' It might have been unfortunate for them or for the field, but it is fortunate for you, and everyone knows it.
The introduction should lead up to, and conclude with, a statement of how you intend to approach your question and why your approach is an improvement on past efforts (or why it is worth undertaking even if it isn't). This is essentially what is new about your approach, your particular contribution. It need not be anything great. Something like ``applying X's method to test Y's theory'' is good enough.
Method. This section gives the details of how you went about your project. It is usually divided into subsections such as subjects, materials, and procedure. These subheadings are standard ones, but they are not always appropriate, and other subheadings are acceptable. The point of subheadings is that the reader may want to skip this section entirely and return to it later in the paper. The subheadings should make it easy to find relevant details.
Results. This is a summary of what you actually found. It is not a dump of your unanalyzed data, nor merely a report of whether your statistical tests were significant, but somewhere in between. It should contain whatever summary statistics will help readers see for themselves what happened, such as means and standard deviations of various conditions, and raw correlations, when these are relevant. It should also contain the results of statistical tests. Make sure to do and report just those tests that are relevant to the question that inspired your project. If you must include your raw data (and sometimes there is good reason to do this), put them in an appendix. (Notice that the word ``data'' is a plural noun meaning, roughly, facts.)
Graphs, charts, and tables are often useful in this section (and elsewhere, but less often). They should be labeled consecutively either as Figures or Tables, depending on whether a typesetter could be expected to set them, (yes for tables, no for figures), e.g., Figure 1, Figure 2, Table 1, etc. Each one should have a caption explaining clearly what it is, if possible without relying on anything in the text. (Figure captions are on a separate sheet so that the typesetter can set them, but for course papers, this is not necessary.) The text should tell the reader when to look at the figures and tables (``As shown in Figure 1 ...''), and it should point out the important points, but it should not simply repeat in writing what they say.
Figures and tables are supposed to go at the end of the paper, but this is for the benefit of the typesetter. Most professors (except nitpickers) prefer the tables and figures close to where they are needed.
Discussion. It is a good idea to begin the discussion with a summary of the results, for the benefit of the reader who wants to skip the results section (and to remind the reader who didn't skip it but got interrupted by a phone call and forgot it).
In the rest of this section, you return to your original question and tell the reader what your results have to say about it (``The results indicate that ...'') and what they do not have to say (``However, the results are inconclusive concerning ...'' or ``do not speak to the question of''). In each case, tell why. Try to think of objections that someone might make to the conclusions that you draw (whether the objections are correct or not) and either answer them or qualify your conclusions to take them into account (``Of course, these conclusions assume that the subjects were telling the truth, which might not be the case''). You may also say why you think the objections are weak even if they are possible (``On the other hand, there was no reason for the subjects to lie''). Your task here is not to do a sales pitch for some idea but rather to help the reader understand exactly what can and cannot be concluded.
The discussion section may be combined with the results. The advantage of this is that it puts the results in the context of the issues that generate them. The disadvantage is that the flow of the discussion gets interrupted with a lot of statistics, etc.
The discussion section is also the place to say anything else you want to say that does not go anywhere else. You may reflect on the implications of your results, or your methods, or whatever, for other issues that were not the main point of the paper. You can talk about how your project should have been done, and why. Or you can make a more general argument, for which your results are only a part.
Note that some of these things may be quite creative, but none of them amounts to simply reporting ``your own ideas'' without support. You should report your own ideas -- when you can support them with arguments and reply to potential arguments against them. If you can't do this, maybe your ideas need to be changed. You can also make suggestions that might be true, labeled as such, but then try to state the alternative too.
It is often a good idea to end the paper with a general statement of main message. More generally, one type of well-constructed paper will reveal its main ideas to a reader who actually reads only the first and last paragraph and the first and last sentence of every intervening paragraph, and this principle applies especially to the discussion section by itself.
References. This is a list of the articles cited. Usually, articles are mentioned in the text by author and date, e.g., Baron (1988), and the references at the end are listed alphabetically by author. Each discipline and each journal has its own conventions about references. These usually insure uniformity, but they don't even help the typesetter. The important thing is that you give the reader what she needs to find the articles you have cited. For journals, both the volume and the year are usually needed as well as the page numbers, because mistakes are common. If you really want to do it ``right'' pick a journal and imitate the style.
Footnotes. Sometimes you want to say something that isn't quite necessary. This is the time to use a footnote. If you can get away without using them, it saves the reader's eyes. But sometimes it's hard to resist making rather extensive, but rather tangential remarks. These go in footnotes, not the text. The really eager reader will read them. Others will not.