"Staff education has turned out to be incredibly important. You still go to places where the contactless terminal is buried under bags of snacks, but most places have trained their staff to know what these technologies are. At first, it seemed odd that retailers had put these terminals in and some staff had never heard of them. But it's an environment with high staff turnover and lots of people on fairly low pay - how long are companies going to spend training them?
"Having said that, McDonald's has always struck me as somewhere that went to a lot of effort to make sure its staff knew exactly what was going on.
"Customer education is difficult. Most people throw things like fliers straight in the bin, so what you need is for people to learn from seeing others doing something. In retrospect, it might have been easier to get things moving if public transportation had been sorted a bit earlier - getting people used to seeing others tapping their cards. Just showing TV adverts doesn't do it.
"It's also important to use contactless in more areas where it has a bigger competitive advantage against cash. It's great that contactless works picking up a sandwich or a coffee, but it doesn't fundamentally change the experience. Contactless wristbands at a pop festival, using your phone to pay for a bus journey - these are the things that transform your customer experience.
"I'd also say that retailers don't always use contactless most effectively at the point of sale (POS). You go into a shop, they ring something up, you go to tap and they say the terminal isn't turned on. They have to go back to the POS to press another button and turn on the contactless terminal because they're treating it as just another card, and it really isn't.
"As soon as you ring something up, the contactless terminal should light up. If you treat these new mechanisms as just another card, you really don't get the full benefit from them.
"I know a lot of people who are uncomfortable with contactless because of a lack of PIN. That problem applies to cards, but not to phones, as people seem to see them as a new environment, which they treat differently.
"The industry's spent ages teaching people to put their PINs into merchant terminals and I think that's probably going to be seen as a mistake. We should've been telling people to never put your PIN in something that isn't yours. It's much safer to buy something in a store and put your PIN into your own phone than into a terminal."
Follow Dave on Twitter @dgwbirch