The Tuesday afternoon test
Picture the actual moment somebody finds you. They are between two other things, on a phone, possibly with one hand, possibly on poor signal. They have about eight seconds of patience.
Design for that moment and the desktop version looks after itself. Design for a twenty-seven inch monitor and the phone version is a compromise.
The details that lose you calls
A phone number that is not a link, so it cannot be tapped. A PDF menu that opens at four per cent zoom. A form with fourteen fields. Pinch to zoom switched off so nobody over forty can read the pricing.
Each of these is a one line fix and each of them individually costs you customers.
Speed is a design decision
Every second of load time costs conversions. On mobile data the difference between a one second and a four second homepage is most of your traffic.
The usual culprit is photographs uploaded straight off a camera at eight megabytes each. Nobody notices because everyone testing the site is on the office wifi.