Tips for Writing Technical Papers

Paper Title
Titles can be long and descriptive:
Linear-Time External Multipass Sorting with Approximation Guarantees
or short and sweet:
Approximate External Sort
Hector believes it's important for the paper (or at least the algorithm) to have a cute name that sticks in people's minds:
Floosh: A Linear-Time Algorithm for Approximate External Sort
The Abstract
State the problem, your approach and solution, and the main contributions of the paper. Include little if any background and motivation. Be factual but comprehensive. The material in the abstract should not be repeated later word for word in the paper.

Related Work
The perennial question: Should related work be covered near the beginning of the paper or near the end?
Beginning, if it can be short yet detailed enough, or if it's critical to take a strong defensive stance about previous work right away. In this case Related Work can be either a subsection at the end of the Introduction, or its own Section 2.

End, if it can be summarized quickly early on (in the Introduction or Preliminaries), or if sufficient comparisons require the technical content of the paper. In this case Related Work should appear just before the Conclusions, possibly in a more general section "Discussion and Related Work".
The Body
Critical rule of thumb: A clear new important technical contribution should have been articulated by the time the reader finishes page 3 (i.e., a quarter of the way through the paper). Aside from this rule of thumb, which applies to every paper, the structure of the body varies a lot depending on content. Important components are:
Running Example: When possible, use a running example throughout the paper. It can be introduced either as a subsection at the end of the Introduction, or its own Section 2 or 3 (depending on Related Work).

Preliminaries: This section, which follows the Introduction and possibly Related Work and/or Running Example, sets up notation and terminology that is not part of the technical contribution. One important function of this section is to delineate material that's not original but is needed for the paper. Do it concisely -- remember the critical rule of thumb.

Content: The meat of the paper includes algorithms, system descriptions, new language constructs, analyses, etc. Whenever possible use a "top-down" description: readers should be able to see where the material is going, and they should be able to skip ahead and still get the idea. In general the paper should tell a story. (Don't, however, fall into the common trap of telling the entire story of how you arrived at your results. Just tell the story of the results themselves.)