You can ensure high scannability of your QR Code in three ways:
1. Print your QR Code on a flat surface. QR Codes don't work if they are printed on uneven or curved surfaces. Hence, make sure your QR Code is printed on a smooth, plain surface.
2. Make sure there is high contrast between the background and your QR Code elements
if your background is dark in color, keep the color of QR Code elements light, and vice-versa.
3. Make sure the size of your QR Code is big enough to be scanned
The size is important while working with QR Codes. So your must calculate the ideal size of QR Code images for your campaign. Read this guide to know more: QR Code minimum size.