$sudo pacman -S gnome gnome-extra gnome-tweak-tool
For Login Manager you can use LXDM or GDM
$sudo pacman -S lxdm
$sudo pacman -S gdm
then enable it:
$sudo systemctl enable lxdm
$sudo systemctl enable gdm
I prefer using lxdm than gdm because it's fast than gdm. But for prefer looks gdm is best.
After you installing gnome, then restart, and login with gnome session.
Here's default of gnome 3.
Default Start Menu is available on Activities
Window List (also on activities)
That's default of Gnome 3, for me it's not look comfortable, but don't worry Gnome 3 have extensions for customize your gnome 3.
Here's some extensions that maybe useful to make gnome 3 comfortable. One click install from web. (you must integrate gnome 3 with browser, there will be notification if you open it).
To enable extensions after installation, open Tweak Tools, and go to Shell Extensions, then turn on to enable.
1. Apps Menu / Start Menu
Slingshot App launcher:
2. Desktop Icons
After you enable on Tweak tools, enable it from user option.
And here's some desktop icons that avilable:
3. Windows List
Classic Windows List:
Alternative way you can use cairo-dock to make looks eyecandy. :D (this not gnome extensions).
Ok that's it.
Enjoy GNOME 3 on Archlinux