How do I know what packages to install?

The unstable builds of FS Icons Ubuntu come in 4 main flavors, with 3 sub-themes within each:

1. FS Icons Ubuntu - the main pack (fs-icons-ubuntu)
  - FS Icons Ubuntu - mono dark (fs-icons-ubuntu-mono-dark)
  - FS Icons Ubuntu - mono light 1 (fs-icons-ubuntu-mono-light-1)
  - FS Icons Ubuntu - mono light 2 (fs-icons-ubuntu-mono-light-2)

2. FS Icons Ubuntu MEgypt - slightly sandy look (fs-icons-ubuntu-megypt)
  - FS Icons Ubuntu MEgypt - mono dark (fs-icons-ubuntu-megypt-mono-dark)
  - FS Icons Ubuntu MEgypt - mono light 1 (fs-icons-ubuntu-megypt-mono-light-1)
  - FS Icons Ubuntu MEgypt - mono light 2 (fs-icons-ubuntu-megypt-mono-light-2)

3. FS Icons Ubuntu Sky - bluish tint (fs-icons-ubuntu-sky)
  - FS Icons Ubuntu Sky - mono dark (fs-icons-ubuntu-sky-mono-dark)
  - FS Icons Ubuntu Sky - mono light 1 (fs-icons-ubuntu-sky-mono-light-1)
  - FS Icons Ubuntu Sky - mono light 2 (fs-icons-ubuntu-sky-mono-light-2)

4. FS Icons Ubuntu Uva - purple-ish tint (fs-icons-ubuntu-uva)
  - FS Icons Ubuntu Uva - mono dark (fs-icons-ubuntu-uva-mono-dark)
  - FS Icons Ubuntu Uva - mono light 1 (fs-icons-ubuntu-uva-mono-light-1)
  - FS Icons Ubuntu Uva - mono light 2 (fs-icons-ubuntu-uva-mono-light-2)

The package names for each set are found in parentheses to the right of the name.

The mono dark packages work well with dark themes, and the mono light packages work well with light themes.

Each of the 4 main flavors require either mono dark, mono light 1, or mono light 2 to function properly (e.g. fs-icons-ubuntu-sky needs either fs-icons-ubuntu-sky-mono-dark, -mono-light-1, or -mono-light-2 to function as intended).

To install the packages, see this FAQ: https://answers.launchpad.net/fs-icons-ubuntu/+faq/2006