The ability to communicate clearly and effectively in writing is essential for your university career. Here are some print and online resources to consult for questions on style, points of grammar, etc.
William Strunk Jr. and E.B. White, The Elements of Style (4th Edition) (aka "Strunk and White")
This is probably the most useful little book on writing you will ever read. It is short enough to read in one sitting and sufficiently well-organized to serve as a ready reference for almost any issue in writing. E.B. White was a renowned journalist and the author of the timeless children's classic Charlotte's Web . Highly recommended!
In-print or online at: The Elements of Style
Joseph Gibaldi, MLA Handbook for Writers of Research Papers, 7th Edition
The reference manual for MLA citation style and standards for document preparation. Also has sections on the process of research and the mechanics of writing.
In-print. A summary of MLA style is online at Purdue's Online Writing Lab (an overall excellent source!): MLA Formatting and Style Guide
Kate L. Turabian, A Manual for Writers of Research Papers, Theses, and Dissertations, Seventh Edition: Chicago Style for Students and Researchers (Chicago Guides to Writing, Editing, and Publishing)
The reference manual for "Turabian" or "Chicago" style citations and document preparation standards. Like the MLA manual, it also contains sections on the mechanics of writing.
Turabian's manual is a simplification of the The Chicago Manual of Style, 16th Edition, which is the industry standard for many publications around the world. If you are taking on more advanced writing projects, it is worthwhile to purchase the Chicago Manual itself, which is far more extensive and contains guidance on all aspects of writing, editing, and citation.
In-print. A summary of Chicago/Turabian style is online at Purdue's OWL: Chicago Manual of Style 16th Edition
There is also Chicago's own Quick Citation Guide
"Advice on Academic Writing", from the University of Toronto
Purdue University's "Online Writing Lab (OWL)"
A very useful site filled with all sorts of information on the different aspects of academic writing. Any concern you may have in writing is likely to be addressed here.
George Orwell, "Politics and the English Language"
An essay on style from the author of Animal Farm and Nineteen Eighty-Four – one of the greatest writers in the history of English literature. Highly recommended!