Do play it cool.
If you go into a shop to restock your cards and see someone buying one, try and play it cool. Don’t pull unsubtle faces behind them at the shop man like, ‘Look, they’re actually buying my shit.’ He’s not stupid. They’re paying for it at the till. He is literally picking it up and putting it in a bag for them. He knows.
Plus, if you’re not careful, it may lead to you being introduced to the buyer as the designer and then having to deal with first hand compliments. They’re the worst kind. And when you’re already taken aback that you’ve just witnessed someone buy your stuff of their own freewill, you’re definitely not going to play it cool when real-life praise comes your way.