There are a large number of excellent textbooks geared specifically to attaining reading knowledge of a language that are frequently used by students preparing for graduate foreign language proficiency exams. Among them, a series of texts entitled French [or Spanish or German] for Reading put out by Prentice Hall and co-authored by Karl C. Sandburg is useful. Likewise, a number of relatively inexpensive workbooks that provide practice with verb tenses and basic grammar can help students brush up on the basics. An online course in a language for reading knowledge might also help you prepare for this exam. For instance, Continuing Studies at the University of Wisconsin-Madison offers French for Reading Knowledge in a one-year course that can be started at any time (http://continuingstudies.wisc.edu/classes/online-french-for-reading-knowledge.html). After completing a course like this, you will likely be well-prepared for our translation exam.
Practicing translation is also very useful. You might find it helpful to look at bilingual texts with facing page translations. This allows you to read professional translations and to compare those translations to your own.
Finally, you might look for language courses specifically aimed at developing reading knowledge. Although GMU does not offer such coursework, other universities in the DC metro area do offer such classes. These classes could be used in preparation for taking the exam.