1. The official website of the United States Tennis Association (USTA)
2. The official rules of tennis
And the Code of tennis governing unofficiated matches
3. The basic rules of tennis (in simple terms)
http://www.buzzle.com/articles/basic-rules-for-playing-tennis.html
4. The rules of tennis, in common language, but with lots of details and etiquette and such
http://blue.utb.edu/jloff/1127/ch4/ch4.htm
5. Get a grip
http://www.tennis.com/articles/templates/instruction.aspx?articleid=1337
6. Behave yourself
http://tennis.isport.com/tennis-guides/proper-tennis-etiquette
http://tennis.about.com/library/weekly/aa092899.htm
7. Tennis rules quiz time
http://tennis.about.com/od/faqandreference/l/aarulesquiz.htm
http://www.tennis4you.com/quizzes/quiz002.htm
8. Managing the mental/emotional side of the game
What Type of Player Are You (and how can you use that knowledge to your advantage?
http://www.tennisserver.com/turbo/turbo_00_11.html
Make Your Mind Your Best Ally:
http://www.tennismindgame.com/
Learning How to Accept Mistakes You Make in Tennis:
http://www.feeltennis.net/how-to-be-at-peace-with-mistakes-in-tennis/
Playing Well Under Pressure:
http://www.tennismindgame.com/playing-under-pressure.html
When Perfectionism Helps and When It Hurts:
http://www.tennismindgame.com/perfectionism.html
How to Handle Anger as a Tennis Player:
http://www.tennisserver.com/turbo/turbo_02_12.html
9. A few things to think about when it comes to strategy
http://www.teachingtennis.com/site/strategy.htm
10. What it means to have a championship culture
10 Things Teammates Don't Let Teammates Do in Championship Cultures