Dan Leberman, Vice President North American Online Small & Medium Business Unit, PayPal
Beginning Tuesday, April 21st, 2015, Google 
“Starting April 21, we will be expanding our use of mobile-friendliness as a ranking signal. This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results.” 1
What does this mean for small businesses?
If you haven’t yet optimized your website for those searching (and shopping) on mobile devices, it could possibly mean that you now rank lower in all mobile searches, which make up about half of all searches:
Mobile comprised almost half of all Google traffic from June 2014 to November 2014, with 52 percent coming from desktops and 48 percent from mobile.2
How can you optimize your website for mobile?
Lessons from retailers who already have mobile-optimized experiences can help the rest of us still on our way to the mobile eCommerce promised land. So, what have we learned from those on the mobile-cutting-edge?
Ensure your mobile experience is in fact mobile-optimized.
Don’t assume that your desktop website works just as well for mobile viewing. Pick up your phone and see how user-friendly it is. Google Developers has a mobile-friendly test you can take.3 If needed, look for a developer or third-party platform provider (such as BigCommerce) to help you launch a mobile-responsive experience.
Decide how you want to optimize your shopping and checkout experience for mobile.
There are three ways to help configure your shopping and checkout so that you have the best possible experience for mobile shoppers:
Responsive web design
Probably the simplest approach, your goal here is to build ONE website (that is, one URL, one set of HTML, etc.) that looks great no matter what device or size screen it’s viewed on.
Dynamic serving
This takes the above one step further by actually serving up TWO sets of code (essentially, two different websites) depending on the viewing device, for an even more targeted experience to mobile shoppers. Your domain name (URL) stays the same.
Mobile website
Mobile websites use a different domain name (and HTML, etc.) for mobile shoppers. If you’ve ever seen a URL like “m.domain.com”, you’re on a mobile site.
Don’t cut out high perceived-value features.
It’s tough to have a great mobile-optimized experience that has ALL of the functionality of your desktop version. Just remember: mobile shoppers expect to access nearly all of the same features as desktop shoppers, including discount codes and shipping offers.
Checkouts need to be as mobile-friendly as the rest of your site.
One of the most important features of your mobile-friendly site is an easy-to-use checkout process. To help create a mobile-friendly checkout experience:
Ensure the "Add to Cart" and "Checkout" buttons, as well as your shopping cart icon, are easy to find. Place them at the top and bottom of every page. Keeping image use to a minimum, because load time affects site abandonment. Use large buttons that can be tapped easily on a small screen.
Rest assured, PayPal businesses: Our checkout products can detect what device your customers are using, and help optimize the payment experience for them.
When in doubt: Ask the Lion itself
For plenty of detail on this topic, Google Developers has an entire online guide to developing mobile-friendly websites. Included in the guide is a list of common mistakes businesses make when optimizing for mobile SEO.
By carrot or by stick: Change is good
Optimizing your site for the way people search and shop nowadays can only be a good thing: it could result in higher conversion rates and more new customers. And, remember that PayPal and our PayPal Partners are in your corner, ready to help you go mobile.
1Google Webmaster Central Blog, February 26, 2015. http://googlewebmastercentral.blogspot.com/2015/02/finding-more-mobile-friendly-search.html
2ClickZ, January 7, 2015. http://www.clickz.com/clickz/column/2388915/why-mobile-web-still-matters-in-2015
3Links to the Google Developers site and other sites are provided for informational purposes and in no way represents an endorsement or approval by PayPal Inc.
Disclaimer: These tips aim to promote ways for merchants to optimize their websites for mobile shoppers. The information it contains is offered as a guide only and should not be treated as a full statement on the subject.