Set the interface language to English, unless it's a localized screenshot.
Preferably, use the default Plasma settings (icons, color scheme, style, window decoration, application settings etc.).
Preferably, use compositing (Desktop Effects module in System Settings), but don't worry if your graphics card does not support compositing.
Preferably, use font "Liberation Sans" at 9pt.
If the screenshot shows parts of the desktop, preferably use the default background of Plasma. Include a margin (around 20 pixels) if possible, to ensure that window shadows don't look cropped.
Save as a PNG image.
If you are preparing a localized screenshot, use the same name as the original English one, with the language-code (the same as you will see on the page address) appended. Fx, a Spanish version of dolphin_open.png should get the name dolphin_open_es.png
If the screenshot is to update an existing one, use exactly the same name so that the update happens automatically (see Update an Image).
