Customers will come into your cafe looking for a cuddly cat to snuggle. A little star will appear beside the Customer which shows their level. They will also have a little thought bubble with a picture in it which indicates their personality.
Cats can be paired with a customer of the same level or less, so higher level customers will require higher level cats, and you can earn bonus hearts for pairing up a cat and a customer that share the same personality! You can still pair cats and customers with different personalities though with no penalty. Pairing higher-level cats with higher-level customers will earn you more hearts.
Tap on a customer and a spotlight will illuminate them, and a toolbar will open along the bottom of the game showing all the cats available to pair! Then simply tap and drag the cat you think will pair best to your customer up to them and they will pair up for a snuggle!