My recommendation for someone wanting to install Fedora 18, or any distribution that uses an installer they have no experience with, is to devote the first one or two installs to practice. If they work, great. But, if not, it's probably operator error, so figure out what went wrong and try again.
Granted, if you are trying to preserve existing data/partitions, you can't do that. But, you can take it as far as committing the partitions before you back off.
If you just need to devote all of your one and only drive to Fedora, the new installer should be very easy.
Also, with the network install and, I think, the DVD install, you can choose between Gnome 3, KDE, Cinnamon, and XFCE (maybe a couple others). MATE's available in the repositories, but you need to do the install first.