To ensure the quality of NFC communication between a contactless card and a smartphone, a positioning pattern, for example a portion of the card visual, is displayed on the screen of the smartphone. This is a visual aid to help the user to position the contactless card, in proximity to the smartphone, toward a position where a card indicator for which provision is made on the card, typically the portion complementary to the card visual, is aligned with the displayed pattern. The positioning is made easy as the positioning pattern and the card indicator are preferably chosen to be visually complementary. Also, the contactless card is in the appropriate position when the card indicator visually complements the positioning pattern. The positioning pattern is thus displayed at a location of the screen allowing the best NFC coupling between the card and the smartphone.