Let the colours do less
One strong colour is enough. LoyalPack picks black or white text for you based on the colour you chose, so you never have to think about contrast on the card face, but a background picture on top of that is a second thing competing for the same space.
Make the stamps countable
- Pick a mark with a solid shape. Fine outlines disappear at card size.
- Leave Stamp colour empty unless you have a reason. Empty means the marks follow the card text colour, which is already chosen to read.
- If you use a background picture, move the Overlay slider until the stamps separate from it.
Keep the words short
The reward is the one line a customer reads. "Your tenth visit free" works. A sentence with a comma in it does not, because it wraps and stops being a headline. It is printed exactly as you type it, under the word Reward, so it does not need to repeat the stamp count.
The logo
A square logo on a transparent background looks best, because it sits on your colour rather than on a white tile. The one exception is white artwork on a transparent background: Google Wallet now shows your Brand Icon inside a white circle, so a white mark disappears into it and is effectively invisible. Give a white logo a solid background, or use a coloured mark. Anything with fine detail or small print will not survive being shrunk to the corner of a card.
Check it on a phone before you print a poster. A card that reads on a laptop can still be too busy in a hand.