1. Clarity [in terms of content and legibility too]
2. Completeness
3. Brevity
A CV should be properly organised so as to facilitate the reader to get the crux of your academic status at a glance. remember don't fill-in minute details. Your objective must very clear and should be well drafted. There should be no grammatical errors.
Usually every academic institution describes the structure and sections of the curriculum vitae required from its members. thus curriculum vitae is institution based.
The best CV is pretty much the one that gets you the job, promotion or whatever you submit it for, so I second the advice of looking at the CVs of the successful researchers and learning from them.