Case reports make for a nice introduction to writing for publication, since they have to be brief, and often are limited to a certain number of references by journals. The key to getting published is to pick a case that teaches something new and then making it sound important. Do a Pubmed search using keywords from your case to see if anyone has written about it before. You can usually narrow your focus suficiently so that you're presenting a new idea. Where to submit usually depends on the subject at hand (e.g. I submit a lot to Psychosomatics and General Hospital Psychiatry since I'm a consult psychiatrist). Each journal has formatting and length instructions on the "instructions for authors" page on their website.
My formula for a case report is something like:
Introduction (1-2 paragraphs): Introduce the basic topic at hand (e.g. duloxetine is a recently approved dual-action reuptake inhibitor used to treat depression, etc.), and present what you're going to tell them about (We present the case of a patient taking duloxetine who suddenly burst into flames).
Case: Present the case with all relevant data
Discussion: The "meat" of the article - duloxetine works by blah-blah, common side effects are X, Y, and Z. To our knowledge this is the first case of spontaneous combustion associated with duloxetine. (Now for the key phrase...) It is important that psychiatrists treating patients with duloxetine are aware of this potential complication since they may want to invest in an asbestos lined coat, etc.
Throw in a couple of references and submit. Hasn't failed me yet.
We should make this a sticky....
