This web site is borrowed from Purdue University, and is one of the best sources of information concerning almost all questions you may have related to writing a paper.  Please scroll through the entire list of subjects, as you may find more than you were looking for.

• General Writing Concerns
  • Planning/Starting to Write
    • Planning (Invention)
    • Planning (Invention): When you start to write
    • Planning (Invention): Thought Starters (Asking the Right Question)
  • Editing and Proofreading
    • Editing and Proofreading Strategies for Revision
    • Higher Order Concerns (HOCs) and Later Order Concerns (LOCs)
    • Proofreading for Commas
    • Proofreading Strategies
    • Proofreading Your Paper
    • Steps in Editing Your Papers        
  • Coherence
    • Coherence
    • Transitional Devices (Connecting Words)
    • Strategies for Improving Sentence Clarity
    • The Paragraph
    • Paragraphing
• Other Concerns
  • Quoting, Paraphrasing, and Summarizing
• Punctuation
  • Overview of Punctuation
    • Brief Overview of Punctuation: Semicolons, Colons, Parentheses, Dash, Quotation Marks, and Italics: exercise and answer key
  • Sentence Punctuation
    • Sentence Punctuation Patterns
    • Run-ons, Comma splices, and Fused Sentences
• Commas
  • Commas after Introductions: exercise and answer key
  • Commas vs. Semicolons in Compound Sentences: exercise and answer key
  • Commas with Non-essential Elements: 3 exercises and answer keys
  • Proofreading for Commas
  • Using Commas: 5 exercises and answer keys
• Quotation Marks
  • Quotation Marks: exercise and answer key
• Apostrophes
  • The Apostrophe: exercise and answer key
• Hyphens
  • Using Hyphens
• Parts of Speech
• Nouns
  • Count and NonCount Nouns (with Plurals, Articles, and Quantity Words): 2 exercises and answer keys
  • Count and NonCount Nouns (with Articles and Adjectives): exercise and answer key

 

• Pronouns
  • Using Pronouns Clearly
  • Pronoun Case
• Verbs
  • Verb Tenses
  • Verbals: Gerunds, Participles, and Infinitives
• Adjectives and Adverbs
  • Adjective or Adverb?: 2 exercises and answer keys
  • Adjectives with Countable and Uncountable Nouns
• Prepositions
  • Prepositions of Direction: To, On(to), In(to)
  • Prepositions of Time, of Place, and to Introduce Objects
• Other Writing Concerns
• Non-Sexist Language
• Accept/Except and Affect/Effect: 2 exercises and answer keys
• A+ Research and Writing for High School and College Students
• Common Words That Sound Alike
• I Before E: 2 exercises and answer keys       
• Research Papers                                                 
• Citation Information
• Other Online Sources
• Roget's Online Thesaurus
• Elements of Style                                              
• Bartlett's Quotations
• HyperGrammar
• Paradigm Online Writing Assistant
• Purdue University's Online Writing Lab (OWL)