Focus on finding the racket that matches your body type and grip size. To find the ideal grip size, simply make sure it feels comfortable in your grip. Many stores offer demo rackets so you can try them before committing. If you do not have the opportunity to do so, go online for tips on the ideal grip size, weight, and shape for your specific needs.
Another key component to a good racket is the type of strings. Top brands tend to already sell rackets with a good string match. If you happen to break strings, make sure to replace them by good quality strings. For beginner and intermediate levels, a soft string such as natural-gut or multi-filament are great to hold tension and give you a nice, gentle feeling upon ball impact.
Finally, you may enjoy the feeling of adding a shock-absorber to your racket strings, which decreases the amount of vibration when you hit the ball.