To make your fonts on Archlinux looks better you need to install additional fonts. If you didn't install it, the fonts will make your desktop to old. :D, To see the available fonts here from repo or AUR see : https://wiki.archlinux.org/index.php/Fonts
I just choose ubuntu, droid, & dejavu$sudo pacman -S ttf-droid ttf-dejavu ttf-ubuntu-font-family
Done, if you using LXDE desktop, the fonts will change automaticly.
To preview fonts you can install gnome-font-preview
$sudo pacman -S gnome-font-viewer
The apps will be shown on accesories menu "FONT VIEWER"
Here's the screenshot:
If you want to add another fonts, that you download on Internet, and be able to use into your system/apps. open /usr/share/fonts/TTF (enable root acces first on file manager), then paste ttf fonts on there
If you running application like libreoffice, gimp, etc. If the fonts still not added, close the application then running it again.
Enjoy new fonts.