Be sure that the work is eligible to be shared. In order to release your work with a CC license or in the public domain, your work should be cleared from all copyright issues. To do so, your work should be one or a combination of the following types:
Note: For any third party materials, whether openly licensed or copyrighted, those materials need to be attributed as not governed by the CC license you chose for your work, but under different terms and by different authors.
If you must use any items that are copyrighted with all-rights reserved, be sure to obtain the permission letters from the authors.
Creative Commons licenses are non-revocable. This means that you cannot stop someone who has obtained your work under a Creative Commons license from using the work according to that license. You can stop offering your work under a Creative Commons license at any time you wish; but this will not affect the rights associated with any copies of your work already in circulation under a Creative Commons license.
To learn more about basic conditions that you should think about before you apply a Creative Commons license to your work, please visit the website CC Wiki: Considerations for licensors and licensees.