The thrower's ten will help prevent injury by especially working working on the muscles that help stop the forward swing. This allows you to practice longer with very fast swing speeds - the ultmate way to develop power in your strokes.
Thrower's Ten Exercises
http://www.muhlenberg.edu/pdf/main/athletics/athletic_training/throwers10.pdf
(Note that even weightlifters do rotator cuff exercises like those in the thrower's ten to prepare for the rigors of the bench press, and even increase their bench press personal bests.)
I like the following online site for explaining why it is important to approach strength training in stages.
First, you must increase your overall level of fitness/strength so as not to injure yourself during the maximal strength training period.
Finally, only after increasing your maximal strength should you specifically turn to plyometric/power training. (Your stronger muscles will not only set the stage for ultimately more power, but getting the tendons, ligaments and joints strengthened will prepare them for the rigors of power training and help prevent injury.)
The Elite Approach to Tennis Strength Training
http://www.sport-fitness-advisor.com/tennis-strength-training.html
Some belong to a gym and use "machines" to help increase their strength. Most who really look into strength training come to the conclusion that "free weight" exercises actually are a better way to coordinate multiple muscle groups so they act in concert, just as they must for you to play tennis.
Thus, a squat trains the legs, core and the muscles that connect the core and legs - no machine does that.
So you may want to look at this site for a free weight program designed for tennis:
Tennis Weight Training - Exercises of Weight Training for Tennis
http://optimumtennis.net/tennis-weight-training.htm
If you do use free weights get instruction to be sure you have correct technique and don't cause yourself an injury.
Knowledge is power.
The more you know, the more you will appreciate that there is no "cookie cutter" approach that will work for all, be the best approach for
you now, or be the best approach as your strength and tennis game improve.
For more in depth information about why/how to train consider buying:
Tennis Training: Enhancing On-court Performance by Kovacs, Chandler and Chandler
http://www.amazon.com/Tennis-Training-Enhancing-On-court-Performance/dp/0972275975/ref=pd_sim_b_2
And for specific regimens in strength and power training it is hard to beat the information in:
Power Tennis Training by Donald Chu
http://www.amazon.com/Power-Tennis-...616X/ref=sr_1_1?ie=UTF8&qid=1338655452&sr=8-1
Good luck!