First, most handheld devices include a phone, so let’s make our phone numbers clickable:
"To add a separate stylesheet after your main stylesheet and use the cascade to overwrite the rules, use the following.
<link rel="stylesheet" type="text/css" media="only screen and (max-device-width: 480px)" href="small-device.css" />"
"When designing for touch, make sure the tap size (width or height) for the navigation item is at least 30 pixels."
"For users who use their thumbs, 72 pixels does wonders. "