QRCodeContrast and clear space
A dark QR code on a light background is easier to read. Keep the blank border around the code intact and do not place text or a logo in that space.
Size and print surface
A small business card and a poster scanned from a distance need different code sizes. Test at the actual scanning distance. Glossy, curved or uneven surfaces can make scanning harder.
Links and device testing
Check that the link opens the correct page. Scan a printed sample with different phones and in different lighting conditions. Run this test before ordering a full print batch.