Ensure Google understands your mobile solution
In the past search engines were mainly interested in the text of your page, not the other bits. Now it is different. The more information a search engine has about your webpage the more it can understand it.
To check if your resources are blocked (which is unfortunately rather common) use the mobile seo tool.
This is a very important part of mobile SEO
Google may not know your site is mobile if it can not see your CSS.
Now let's say that a mobile user is asking Google for green widgets from a mobile device. Google looks at your page and says "hmm this page is about green widgets, but it doesn't look mobile".
Google then shows the searcher another webpage, not yours.
That could have been you if your CSS wasn't blocked.
Does Google only show mobile results on mobile devices?
No. It does not. However, it is always smart to remember that Google wants to provide the best, most useful, most perfect result for a search query they can. So it is our job to be that result.
Think about this
Right now when a mobile user searches for "green widgets" there are not so many mobile websites that have great content that would be useful to the searcher and are mobile friendly and are fast loading.
Guess what? Soon there will be.
In the near future I do see Google returning results to mobile users that are only comprised of mobile capable websites. Not because Google is saying "we only give mobile sites to mobile searchers" but more because, the best choices for searchers will end up being mobile ready sites because there will be so many of them out there.
If you are blocking your external resources Google won't have the deep understanding of your site it needs to have in order to rank you well.
How to make sure you are not blocking resources
To check if your resources are blocked you can now use our free Mobile SEO tool found here.
Make sure you do not see something like...
If the above is in your robots.txt, then you are likely blocking some resources.
Know what your page loads, and make sure you are not blocking those things from search engines or Googlebot.
Wordpress blocked resources
For Wordpress users there is a common problem of blocked resources. This occurs because often webmasters have blocked the wp-contents and the wp-includes folders of the typical Wordpress installation.
It looks like this in your robots.txt file..
To solve the issue, you would remove those lines from your robots.txt file if they are present.
For any site, Wordpress included, one should check their site for blocked resources.