For a majority of the time a compact disc offers a "deterioration free" method of playing music, since it is based on "optical" transference of information (laser) against mechanical" transference (needle or tape head). For this reason, playing your CD imposes no wear and tear on the disc, unlike both vinyl records and audio cassettes which suffer continual wear from friction caused by their mechanical processes. This does not mean that your CDs are indestructable but nearly all the wear and tear on a CD can be prevented by careful handling. 

Following are guidelines for proper disc handling:

1. Always handle the disc by its edge or center hole. 

2. On no account scratch the CD on the label or play side. A scratch that penetrates the label side will directly destroy a considerable amount of data, surprisingly a scratch on the play side of the disc is often invisible to the CD player and if not can sometimes be repaired.

3.   Refrain from sticking paper or tape on the label surface. While it won't hurt the disc, it could interfere with the CD player. 

4.   Do not write on the label surface with a ballpoint pen or other hard object. This will almost certainly damage the data layer. Also the solvent in a marking pen; could penetrate the label and deteriorate the reflective layer (which would damage the disc beyond repair). 

5.   Do not expose a CD to high temperature or humidity for an extended period of time, high temperatures can warp the disc and cause deterioration of the reflective layer. 

6.   Do not allow CDs to remain out of their cases for long periods of time and handle only when placing them into and removing them from the CD player 

7.   Take extra care with CDs when using them outside. Sand or dirt can cause damage to the label side (which can't be repaired). 

8.   Keep your CDs clean by gently wiping both the label and play side surfaces with a non-abrasive (i.e. soft cotton) cloth prior to and after each use.

http://eil.com/explore/guide/cd_caring.asp