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 squint. They won't pinch and zoom read more. They'll simply move on.

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, "at least the neighbors were happy." The shop was thrilled too, but that's luck, not strategy.
Design for the Thumb
Screens got bigger. Hands didn't. Put the main actions where a thumb naturally rests, toward the lower part of the screen. Buttons need breathing space, roughly the size of a thumb or fingertip, with gaps around them.
If two links sit so close that a tap might hit either one, you've built a digital coin flip.
Speed Beats Beauty
A gorgeous page that takes six seconds to load is a gorgeous page nobody sees. 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 real life. The office Wi-Fi is a luxury.
Make Your Text Easy to Read
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 wants to climb one for entertainment.
Contrast matters as well. Light gray on white looks elegant on a designer's monitor and can disappear on a phone under bright sunlight.
Trim the Forms
Every extra field creates another chance for someone to quit. 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 right keyboard for each field, so a phone number box opens the numeric keypad instead of making people hunt for digits. Small kindness, big lift in completed forms.
Keep Mobile Pop-Ups Under Control
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 ask for their attention.
Test With Real Hands
Emulators lie a little. Grab three actual phones, old and new, and try to finish your main task on each.
Hand one to a friend who doesn't spend much time with technology and keep your mouth shut. Watch where their finger stops. That hesitation is your next set of improvements, written in fingerprints.