Arch Linux provides for several methods of kernel compilation.
Using the Arch Build System (recommended)
Using the Arch Build System is recommended to take advantage of the high quality of the existing PKGBUILD and the benefits of package management. The PKGBUILD is structured so that you can stop the build after the source is downloaded and configure the kernel.
Using the Arch User Repository
There are packages in the AUR with alternate kernel configurations and patches. You can install them as is, or use them as the basis for your custom package instead of starting with the PKGBUILD for the official package. See Kernels#Found in the AUR.
Alternatively, you can compile a kernel without the Arch Build System (the traditional method). This method involves manually downloading a source tarball, and building in your home directory as normal user. Once configured, two compilation/installation methods are offered; the traditional manual method as well as makepkg/pacman.
An advantage of the traditional method is that it will work on other Linux distributions.
Proprietary NVIDIA driver
See NVIDIA#Alternate install: custom kernel for instructions on using the proprietary NVIDIA driver with a custom kernel.