Steps in Developing a Rubric

Determine learning outcomes
4 - 15 items using brief statements
each focusing on a different skill
must be a measurable criteria

Select terms to use in measuring performance range or scoring levels
Needs Improvement...Satisfactory...Good...Exemplary
Beginning...Developing...Accomplished...Exemplary
Novice...Apprentice...Proficient...Distinguished
Numeric scale ranging from 1 to 4 etc. - avoid odd numbers to disallow readers "sitting on the fence" with mid-range scores.
If appropriate, a score of zero may be included.

Write descriptive statements for each range or level. 
Begin with describing the highest level. 
Note the key words used which will generally be what changes as you write the lower performance descriptions.
The lowest level may be the minimum acceptable performance or a description of anticipated flaws in a performance.
Try using words that convey degrees of performance: Depth, Breadth, Quality, Scope, Extent, Complexity, Degrees, Accuracy...
and words that present a clear range, such as from complete to incomplete, major to minor, consistent to inconsistent, always to rarely...