OpenSUSE's official Firefox1 version is usually lower than the latest release of Firefox. For example, the latest version of Firefox is 34, but Firefox 33 is available on the OpenSUSE source. So if you want to use it as soon as possible after the latest version of Firefox is released, it's best to use the Third-party software source 2 provided by Mozilla.
The steps below (I take the OpenSUSE 13.2 operating system as an example):
Add Mozilla Software Source
$ sudo zypper ar-f Http://download.opensuse.org/repositories/mozilla/openSUSE_13.2/Mozilla
Update Software source
$ sudo zypper ref
Install Firefox under the Mozilla software source
$ sudo zypper in Mozilla:mozillafirefox
Where Mozilla is the alias (alias) of the software source set in the first step.
When you install Firefox, you may be prompted to rely on conflicts, as recommended by the OpenSUSE system.