This post is designed to give you some self-editing help. Everyone has doubts about what they thought they knew while they are editing their own work. That is just the way it is. One second we are positive and the next moment "prominent" looks like it is spelled wrong even though spellcheck says it is okay. So I have some helpful sites you can use as a quick reference. (For the "prominent" problem I would suggest a dictionary. Mine is always next to me when editing or writing.)
Dialogue Punctuation- http://www.be-a-better-writer.
Lay vs Lie, and basically any question you can imagine http://grammar.
Comma refresher complete with quizzes http://grammar.ccc.commnet.edu/grammar/commas.htm
Repeating words- http://thesaurus.com/
What are your favorite sites for grammar rules?