What things should I think about before I apply a Creative Commons license?

Answer:

Applying a Creative Commons license to your material is a serious decision. When you apply a CC license, you give permission to anyone to use your material for the full duration of applicable copyright and similar rights.

CC has identified some things that you should consider before you apply a CC license, some of which relate to your ability to apply a CC license at all. Here are some highlights:

• Is the material copyrightable? If not, is it subject to neighboring rights or sui generis database rights? CC licenses do not apply to material in the public domain. Different countries have different standards for what is in the public domain.
• Do you own the material you want to license? If not, are you otherwise authorized to license it under the specific CC license you are interested in using? You should not apply a license to material that you do not own or that you are not authorized to license.
• Are you aware that CC licenses are not revocable? You are free to stop offering material under a CC license at any time, but this will not affect the rights associated with any copies of your work already in circulation. (Any particular licensee may lose his or her rights after violating the license, but this does not affect continual use of the work by other licensees.)
• Are you a member of a collecting society? If you are, you should make sure that you are able to use CC licenses for your materials.
• Always read the terms and conditions of the specific license you plan to apply. Additionally, there are several terms that may differ in the earlier versions of the license, both unported and ported. If you choose to use a pre-4.0 version or any ported version, clauses such as choice of law may affect your desired choice of license.