Guide to Grammar and Writing: http://ccc.commnet.edu/grammar/
Rules for Comma Usage:http://ccc.commnet.edu/grammar/commas.htm
Comma Splice: http://ccc.commnet.edu/grammar/runons.htm#splice
Punctuation [not commas]: http://ccc.commnet.edu/grammar/marks/marks.htm
apostrophe: http://ccc.commnet.edu/grammar/marks/apostrophe.htm
Run-on Sentences: http://ccc.commnet.edu/grammar/runons.htm
Punctuating Independent Clauses: http://ccc.commnet.edu/grammar/indep_clauses.htm
Sentence fragments: http://ccc.commnet.edu/grammar/fragments.htm
Notorious confusables: Part 1, a-indeterminate; Part 2
Subject-Verb Agreement: http://ccc.commnet.edu/grammar/sv_agr.htm
Pronoun Agreement: http://ccc.commnet.edu/grammar/pronouns.htm
CLICHÉS AND EUPHEMISMS: http://ccc.commnet.edu/grammar/concise.htm#cliches
plague words and phrases: http://ccc.commnet.edu/grammar/plague.htm
parallel structures: http://ccc.commnet.edu/grammar/parallelism.htm
coherence and transitions: http://ccc.commnet.edu/grammar/transitions.htm