If any file can not be deleted, then you can use the program LockHunter, which removes the active connections of other applications to that file, which allow you to change or delete file.
If you are more of a visual person and would like to organize your folders and files using different colors, than check it out how to use color labels in Mac OS X.
If you dont't want that every time you take a picture with your Android device, it gets instantly uploaded to your Google+ profile, this tutorial's for you.
Remember as a kid you played with a mirror, putting your face to the side of it and your friends were laughing at the funny symmetry of your face and your faces reflection?
If there is a vast number of unimportant unread emails accumulating your Gmail inbox and it's starting to bother you, but you don't have time or nerves to mark them as read page by page, this is what you can do.