Last month, Google announced a pair of new mobile-related ranking signals for its search algorithm. One is mobile-friendliness and the other is for content from apps that users have installed on their phones. You can learn more about taking advantage of the latter here.

Are you looking forward to the mobile-friendly update? Is your site ready to go? Let us know in the comments.

The mobile-friendly signal will take a number of things into account. In a recent article, we went through a bunch of these things based on Google’s own guidance and documentation about how to make a site mobile-friendly. Now, Google is telling webmasters some specific things to avoid in a document called “Avoid common mistakes“. These include:

1. Blocked JavaScript, CSS and image files

2. Unplayable content

3. Faulty redirects

4. Mobile-only 404s

5. App download interstitials

6. Irrelevant cross-links

7. Slow mobile pages.

Blocked JavaScript, CSS and Image Files

Google says to always allow Googlebot acess to the JavaScript, CSS, and image files used by your site so it can see it like an average user. If your robots.txt file disallows crawling of these, Google says it “directly harms” how well it can render and index your content, which can result in “suboptimal rankings”.

Google says to make sure it can crawl this stuff by using the “Fetch as Google” feature in Webmaster Tools, which will let you see how Googlebot sees and renders your content, and will help you figure out and fix issues. Then check and test your robots.txt in WMT, and test your mobile pages with the Mobile-Friendly Test. If you use separate URLs for mobile and desktop, make sure to test both.

Unplayable Content

When your content uses videos or other media that’s not supported on mobile devices (like Flash), users will see a message like this:

Obviously that’s not good for users, so you’re going to want to make sure your content is playable on mobile devices. You can avoid unplayable content by using HTML5 standard tags.

“For animated content rendered using Flash or other multimedia players, consider using HTML5 animations that work across all web browsers. Google Web Designer makes it easy to create these animations in HTML5,” Google says. “Use HTML5 standards for animations to provide a good experience to all your users. Use video-embedding that’s playable on all devices. Consider having the transcript of the video available. This will make your site accessible to people who use assistive browsing technologies or who have browsers that cannot play a proprietary video format.”

Faulty Redirects

Google has been notifying webmasters about fixing faulty redirects since last summer.

Basically, if you have separate mobile URLs, you need to redirect mobile users to the appropriate mobile URL on each desktop version. Don’t redirect to other pages (like the homepage). Google gives you some specific examples of what not to do here.

You can set up your server so it redirects smartphone users to the equivalent URL on your smartphone site, and if a page on the site doesn’t have an equivalent, you can keep them on the desktop page. You can also, of course, use responsive design.

Mobile-only 404s

You also don’t want to show mobile users 404s for pages that work fine on the desktop.

“To ensure the best user experience, if you recognize a user is visiting a desktop page from a mobile device and you have an equivalent mobile page at a different URL, redirect them to that URL instead of serving a 404 or a soft 404 page,” says Google. “Also make sure that the mobile-friendly page itself is not an error page.”

Google also sends notifications about this in Webmaster Tools, and again, if you have a smartphone site on a separate URL, you can set up your server so it redirects smartphone users to the equivalent URL on the smartphone site. Google notes that if you use dynamic serving, you should make sure your user-agent detection is correctly configured. If the page doesn’t have a smartphone equivalent, keep users on the desktop version. You can also use responsive design.

Be sure to check the Crawl Errors report in WMT. You’ll find problem pages in the Smartphone tab.

App Download Interstitials

Google says you should avoid using interstitials for promoting your mobile app because it can cause indexing issues and “disrupt a visitor’s usage of the site”. Instead, it says to use a simple banner to promote the app within the page’s content using native browser and operating system support (such as Smart App Banners for Safari) or an HTML banner or image like a typical small advertisement, which links to the app store for download.

Irrelevant Cross-Links

“A common practice when a website serves users on separate mobile URLs is to have links to the desktop-optimized version, and likewise a link from the desktop page to the mobile page,” Google says. “A common error is to have links point to an irrelevant page such as having the mobile pages link to the desktop site’s homepage.”

Just check your links to make sure they point to the right equivalent page. It’s that simple.

Slow Mobile Pages

Google stresses the importance of making sure mobile pages load quickly. Google has placed a great deal of emphasis on page speed for quite a while now, and thats’ no different when it comes to mobile-friendliness.

To make sure your pages are fast enough, you can use Google’s PageSpeed Insights tool, which will tell if you what (if any) issues are slowing them down. If it says “should fix,” you should follow that advice.

Google has a series of articles on optimizing performance here, and points to this article from bryan McQuade about making mobile pages render in under one second. You can also read through this page on PageSpeed Insights.

Google also ran a poll asking people what they dislike most when browsing the web on their mobile devices. Page speed was by far the biggest annoyance:

Google’s mobile-friendly algorithm update will begin rolling on on April 21. Webmasters are no doubt scrambling to make sure their sites are ready in time, but the good news is that if your site isn’t ready by then, it’s not a huge deal. Google recently indicated that the ranking signal will run in real time, and will run on a page-by-page basis, so if only some parts of your site are mobile-friendly, the parts that aren’t won’t necessarily hurt your whole site. As soon as you make those parts mobile-friendly, it will be reflected in the algorithm.

Do you think this update will make the search experience significantly better? Will this be a positive for businesses? Discuss.

Images via Google