I was confronted with an old issue, that had not been an issue for a while: writing to an external hard drive that was formatted with Windows (NTFS) from my mac. I used to have NTFS-3G (together with MacFUSE) installed and that used to be fine. However, I guess something when a bit eerie with Mavericks as I was not able to get my old solution to work.
So, here is what I did (you will need superuser powers, so be prepared to type your password):
Open a Terminal (Terminal.app) and create a file called stab in the /etc folder. For instance you can type:
$ sudo nano /etc/fstab
You can now enter some information in your newly created file telling MacOS information about your device. If your external drive is called mydevice enter the following:
LABEL=mydevice none ntfs rw,auto,nobrowse
Use tabs between the fields listed above. Save your file and you are now ready to plug your device.
There is a small caveat: Once you do this, your hard drive is not going to appear in your Desktop. But do not disappear, you can still use the terminal to access the drives mounted by going to /Volumes folder as follows:
$ sudo ln -s /Volumes ~/Desktop/Volumes