I presume you mean a CD-RW disk.
The simple answer is to buy only CD-RW disks from top manufacturers as the quality is assured.
A CD-RW does not have the same reflectivity level as a CD-R so quality is especially important. Even more viotal is who actually manufactures the media and who rebadges it under their own brand name.
To find out the best, average, worse products visit:
for the full lowdown on CD-R and CD-RW media and DVD equivalents.