Many people are concerned that they need to do something different in terms of SEO when targeting Mobile/Tablet devices versus more traditional desktop/laptops.
There are two main routes when considering design for mobile devices. Either your website has a responsive design (ie. adapts to the device and browser) or you create a separate mobile site (which has a different url from your main site but is essentially serving the same content.)
Alternatively, you can ignore mobile at your peril! If your site isn't built right, Google will demote you. The biggest mistakes include:
- Faulty redirects to mobile sites and within the mobile site itself.
- Showing unplayable content, mobile specific error pages, incorrect handling of the Google mobile bot.
- Having a flash heavy site when flash doesn't display on certain smart phones (google won't show your site to these users.) If you have a flash site, you need to make sure your mobile site does not contain flash.
- Your mobile redirect sends all traffic to the homepage instead of linking to the internal page the user wanted to see
- Your mobile site is slow
Ultimately, Google recommends that you use a responsive design when creating your website.
Matt Cutts has said that responsive design does not effect your ranking, as all content is coming from the same url - see the video below.
With a dedicated mobile site, you need to ensure that your url's are canonically redirected to the main site so that you are not effected by duplicate content issues and page rank is not diluted.