Single column layout: Flat architecture is more suitable as they have small screen size to view website, vertical scrolling would perform better.
Suitable for both touch and non touch screen device. Your design must deliver equal experience regardless of phone user used whether touch screen or non touch screen.
Limited and important content. You must not prefer to add all detail content just add important content which is mandatory to add for providing basic information.
Clear and flat navigation menu which can be created with small icons as well.
It should be compatible to different smart phone and all remote gadgets from which it can be viewed regardless of specific mobile browser used or operating system it supports.
You mentioned all the design aspects, but above all a mobile website has to be insanely fast if it has to rank in Google and other search engines. Optimizing mobile websites for voice search is also a challenge.
1. Responsive Website Design
2. Clear Call to Action
3. Click to Call Functionality
4. Simple Forms that Adapt to Mobile Screens
5. Maps & Directions