Mobile websites design begins with an awkward truth. Most of your visitors are holding a phone, probably in a queue, possibly while a toddler tugs at their sleeve. They won't strain their eyes. They won't zoom in and out set up a website. They'll simply go somewhere else.
My aunt learned this the hard way. She tried to order a pizza from a local shop's site, missed a tiny button, and ended up with three pizzas. "Well," she said, "the neighbors were thrilled." The shop was thrilled too, but that's good fortune, not a strategy.
Give Thumbs Some Space
Screens got bigger. Hands didn't. Put the main actions where a thumb naturally rests, near the lower middle of the display. Buttons need plenty of room, roughly the size of a fingertip pad, with gaps around them.
If two links sit so close that a tap might hit either one, you've built a digital coin flip.
Performance Comes Before Looks
A gorgeous page that takes six seconds to load is a gorgeous page people will abandon. Compress your images. Drop the giant background video. Cut the scripts you added "just in case" three redesigns ago.
Test on a mid-range phone with a mediocre connection, because that's how many people actually browse. The office Wi-Fi is a fairy tale.
Words Should Be Readable Without Effort
Set body text at around 16 pixels or larger. Keep lines short. Split up long blocks of text. A wall of text on a small screen feels like an actual wall, and nobody climbs those for fun.
Contrast matters as well. Pale gray text on a white background looks elegant on a designer's monitor and becomes difficult to see outdoors.
Trim the Forms
Every extra field costs you people. Ask for an email, maybe a first name, and leave it at that. Skip the fax number—yes, somebody out there still asks.
Use the appropriate input type for every field, so a phone number box opens the numeric keypad instead of making people hunt for digits. That little convenience can make a noticeable difference in form completion.
Don't Let Pop-Ups Take Over
A full-screen pop-up on a phone is a terrible interruption. Search engines dislike them, and so do humans.
If you really need one, use a slim banner with an obvious close button, and give visitors a few seconds to read before you interrupt them.
Test With Real Hands
Emulators can hide real-world problems. Grab three actual phones, including an older and a newer model, and try to finish your main task on each.
Hand one to a friend who isn't particularly technical and keep your mouth shut. Watch where their finger hesitates. That hesitation is your next set of improvements, written in fingerprints.