How can I make an icon for my new launcher?

Question

I just created a new launcher, for teamspeak. This is the contents:

[Desktop Entry]
Type=Application
Terminal=false
Name=unmount-mount
Icon=/usr/bin/TeamSpeak/TeamSpeak.i‌​co
Exec=/usr/bin/TeamSpeak/runscript.sh

How can I create an icon that will look good in both the launcher and the Alt + Tab switcher, and the dash? How big does it have to be, and what format should I make it?

Answer 1

First, the icon

Just made you one. ^{_{CC SA 3.0.}}

Adapted from aleixoteixeira's design.

Get the SVG here - ubuntu will scale it and it will never be blury because it's an SVG file.

What to do with it now?

I save all my icons in either /usr/share/icons/ or /usr/share/icons/current_pack. It makes no difference, and I don't know what is better practise.

png will scale, but when it tries to scale it bigger will look blurry. Only vector graphics files do, so for this svg is best.