As we are discussing portable photo printers here, so we assume that it can happen using a mobile phone only as computers are not a reliable way to choose if we are on a trip. So, using a mobile phone, we have multiple ways to connect to a photo printer, such a Wi-Fi, Bluetooth, and NFC as well. But, out of all these ways, we prefer Wi-Fi connectivity more as it is faster than any other method. Also, some people might struggle using the NFC feature as it is not available on every smartphone yet. And Bluetooth is slower as we compare it to Wi-Fi. So, in conclusion, Wi-Fi is the best way to connect to a portable photo printer.