basically, OWL Purdue is everything.
Source Citation
MLA Guidelines: http://owl.english.purdue.edu/owl/resource/747/01/
In-Text Citations: http://owl.english.purdue.edu/owl/resource/747/02/
Formatting Quotations: http://owl.english.purdue.edu/owl/resource/747/03/
Basic Works Cited: http://owl.english.purdue.edu/owl/resource/747/05/
Academic Writing
Thesis Statement: http://owl.english.purdue.edu/owl/resource/545/01/
Rhetoric: http://owl.english.purdue.edu/owl/resource/625/01/
Arguments: http://owl.english.purdue.edu/owl/resource/588/01/
Paragraphs: http://owl.english.purdue.edu/owl/resource/606/1/
Writing, Generally
Proofreading: http://owl.english.purdue.edu/owl/resource/561/1/
Concision: http://owl.english.purdue.edu/owl/resource/572/1/
Active & Passive Voice: http://owl.english.purdue.edu/owl/resource/539/1/
Sentence Variety: http://owl.english.purdue.edu/owl/resource/573/1/
Clarity: http://owl.english.purdue.edu/owl/resource/600/01/
Mechanics: http://owl.english.purdue.edu/owl/section/1/4/
Punctuation: http://owl.english.purdue.edu/owl/section/1/6/
Miscellaneous
Email Etiquette: http://owl.english.purdue.edu/owl/resource/694/1/