Much of the documentation I read on the World Wide Web suggests using revisor to create a custom Spin of Fedora. I find that revisor is not well suited to my needs. I use LiveCD Creator. To install it:
yum install livecd-tools -y

I suggest you install the fedora-kickstarts and spin-kickstarts packages as well.
yum install spin-kickstarts* -y

Another tool I use is liveUSB-Creator.
yum install liveusb-creator -y

Once you have those installed you can use your favorite text editor to modify the existing Kickstart files to suiit your needs.
The files are installed by default to the /usr/share/spin-kickstarts/ directory. Be sure to save the files as different file names once you have edited them to suit your needs.
I save them as fedora-custom-base.ks and fedora-custom-kde.ks

Once that is completed you can run the liveCD Creator to create the custom spin in the directory you wish to save the .iso image to.
setenforce 0
livecd-creator
--config=/usr/share/spin-kickstarts/fedora-custom-kde.ks
--fslabel=F13x64-Custom

If that command completes successfully, you will have a F13x64-Custom.iso in the directory. If it does not, the kickstart file has an error.

Next you can use the LiveUSB-Creator tool to burn that custom image to a USB drive. Be sure to create an overlay when doing so. I use 1024M as my overlay size.

For a more detailed article on creating a LiveUSB drive visit the following:
Howto LiveUSB