When printing make sure that the photo fills the full A4 page.
To apply the photo intervention you can download one or more photo packages from the website. These packages you can find under Photo series.
Choose a package you like and press the green download button at the top right side of this page to download at once all photos of this package. Then you can print the downloaded photos and use them for a photo intervention.
Make sure that the photo is visible in the light. Preferably sit with your back towards the window.
To discuss 20 photos you need approximately half an hour. Although one may customize this.