Numerous books have been written about resumes and many career professionals will try to convince you that there are hard and fast rules about proper resume drafting. What follows are my own thoughts and observations about resumes (in a very distilled form) along with some good samples that I have seen (and redacted).
Preparing a resume addendum can help to highlight the particular experience you have had and the responsibilities you assumed. The addendum is usually in the form of a case or transaction summary and can be divided up by type of case/transaction. It can also be organized functionally by skill (e.g. Motion Practice, Discovery, Trial Practice). Preparing such a summary is also a useful exercise in helping you to take stock in what you have done to date. It also helps to prepare you for an interview
A resume is a direct mail marketing piece (which may or may not arrive by mail). It is only designed to help a candidate secure an interview. The piece should be error free, accurate and tailored to the particular position for which the candidate is applying.
It is my belief that many professionals in a job search spend too much time and energy thinking about and perfecting their resume (I was one of those professionals). Time spent getting the wording on the page absolutely "perfect" could be better spent networking.
Your resume is a summary that should emphasize those skills and experiences that are relevant to the job you want. It should not be a summary of everything that you have ever done or even necessarily every law related activity you have ever been involved with (unless omitting the information would distort your background or leave large gaps of time that go unexplained or unless the experience clearly demonstrates that you have closely related skills and experience).
In many ways, it is similar to writing a brief. When drafting a brief, a good lawyer will include only her best arguments, not every argument that she can articulate. Similarly, a good advocate is very selective about which facts to include in a brief while being sure not to distort the case. If you were applying for an in-house position with a company that does a lot of acquisition work, for example, it would be a good idea to include anything you have done that relates to mergers and acquisitions; but your pro bono work with the District Attorney's office is probably less relevant.
make sure at least one other person proofreads your resume
have a few versions for the different kinds of jobs that you are considering
in addition to your general responsibilities, try to list specific examples of your accomplishments. Include case names if they might be recognized by the intended reader
put the most important information first. Typically, this means putting education below your work experience. It can also mean putting dates in a less prominent place. For an example of this see my training resume
where possible, and if impressive, try to quantify your accomplishments (e.g. "extensive corporate transactional experience including significant involvement in over 50 mergers;" "drafted and argued over 100 motions")
don't obsess about whether your resume should be one or two pages. Anyone who proclaims that resumes should never be more than one page may be right with respect to some readers, but entirely wrong with respect to others
try to do something to make your resume stand out of the pack, realizing that attorneys reading the resume will not react well to something that is too unusual
use language and formatting to emphasize what you think is important and de-emphasize what is not really important (in my training resume, I emphasize activities and accomplishments that lead the reader to the conclusion that I know how to design training for lawyers. I have not overly emphasized my experience as a mediator.) You may want to consider attaching a selected list of transactions that you have worked on, a description of their magnitude and something impressive about your role