As with most things in life, mobile search engine optimization (SEO)\u2014the art and science of ensuring your content is easily found on tablets and smartphones\u2014comes with a carrot and a stick.First, the carrot. All those people browsing the Web and using apps on their mobile browsers are often highly motivated to take action\u2014such as buy a product or service from your site. For example, Mobile Marketer estimates that 70 percent of all mobile searches result in user action within one hour. Nine out of 10 mobile searches lead to some action, and over half of the time, it's a purchase, according to Search Engine Land. Ensuring your content is easily found by mobile users and renders well on their screens could deliver a bottom line boost.Now, the stick. If you don't optimize your site for mobile users, you could get left behind. According to Gartner, mobile devices are expected to overtake PCs as the most common Web-access devices worldwide by 2013, while a BIA\/Kelsey report predicts mobile local search volume will surpass desktop local search for the first time in 2015.Mobile search is big and getting bigger. Some estimates suggest that mobile search now accounts for 25 percent of all U.S. search traffic. Users are increasingly tapping keyword searches on touchscreen keyboards. They're also asking questions of Siri, Apple's virtual assistant that rolled out to more iOS devices on Sept. 19, and Google Now, the virtual assistant that debuted in Android 4.1 Jelly Bean.The good news is that mobile SEO doesn't require significant changes as compared to your desktop SEO strategies, says Vanessa Fox, author of Marketing in the Age of Google and founder of Nine By Blue, which provides search analytics software and SEO training. SEO best practices\u2014using relevant keywords in title tags and H1 headers, developing great content that people will engage with, attracting quality links from other sites, and so on\u2014are essentially the same with mobile and desktop, she adds.That said, Google does have Googlebot-Mobile, which crawls and indexes content specifically optimized for feature phones and smartphones in order to serve the mobile user the best content based on the device (feature phone vs. smartphone) he or she is using. Googlebot-Mobile works in addition to Google's desktop crawling and indexing technology.As a result of Googlebot-Mobile, a Google query performed on a mobile device might receive different search results from the same query performed on a desktop computer. It's likely that Google will also develop Googlebot-Tablet to crawl and index content designed for tablets, says Michael Martin, SEO manager for Covario, an SEO and SEM agency for enterprise clients.Tip: Why Your Company Should Hire a Dedicated SEO SpecialistHere are five strategies, tips and best practices to ensure you get the most targeted mobile device users while delivering the best experience to them.1. Know Your Options for Serving Web Content to Mobile UsersYou can follow all the best SEO practices in the world\u2014but if mobile users find your site through a search, go to it on their device, have a bad experience and then click away, all your SEO work has been for naught, at least as far as the growing mobile contingent is concerned, Fox says.How-To: 25 Link-Building Tips to Drive Traffic to Your WebsiteAccording to Limelight Networks, 80 percent of people abandon a mobile site if they have a bad user experience. "You've worked hard, and you've still lost that customer," Fox adds.You need a plan for serving your content to mobile users in a way that delivers a positive experience. There are three ways to deliver Web content optimized for display on phone and tablet screens, says Bryson Meunier, director of SEO strategy at digital marketing agency Resolution Media. \n\nMobile URLs. In this scenario, each desktop URL has an equivalent, different URL, such as m.yoursite.com, which serves up mobile-optimized content.Dynamic serving. With dynamic serving, the server responds with different HTML and CSS on the same URL, depending on the device requesting the page. While you don't change the URL you might create content specifically for mobile users, Meunier explains.For example, if you're a sports site that a mobile searcher has reached by typing latest tennis scores in Google, you might deliver a streamlined mobile-only page that simply lists scores. When someone Googles that same phrase using a desktop browser, on the other hand, the page you serve up might have a lot more information, such as photos about players and teams, in addition to the latest scores.Responsive design. This is the method Google recommends for webmasters for three main reasons.It uses a single URL. According to Google, this "makes it easier for your users to interact with, share and link to your content," and it "helps Google's algorithms assign the indexing properties for the content." Having one URL also helps you build and maintain link equity for that URL, Meunier adds. \n\nPage loading time is reduced, since no redirection is involved to get to a device-optimized page. Plus, Google warns, "user agent-based redirection is error-prone and can degrade your site's user experience."\n\nResponsive design saves resources for your site and for Google's crawlers. "For responsive web design pages," Google says, "any Googlebot user agents needs to crawl your pages [only] once, as opposed to crawling multiple times with different user agents, to retrieve your content. This improvement in crawling efficiency can indirectly help Google index more of the site's contents and keep it appropriately fresh."How-To: Top 10 Things to Look for in an SEO ExpertIn short, responsive design is good for Google and for users. But there are exceptions, as you'll see.2. Choose an Option That Makes Sense for Your Target Audiences.Knowing which option is best requires you to understand your mobile user's needs and intentions, Meunier says. Responsive design is appropriate if your mobile and desktop users are usually looking for the same things, as they are with a news site. By comparison, responsive design might not work as well when your mobile users are looking for one or two specific things, while your desktop audience might be interested in learning a lot more. For instance, mobile users that search for a particular fast-food chain might just be looking for the closest location. Desktop visitors might want menus, nutrition or other information. This would only get in a mobile user's way and slow him down.Additionally, responsive design might not be the best option if your company is hoping to grow its international customer base, he adds. Feature phones are still widely in use in many countries outside the U.S., and responsive-designed sites don't display properly, or at all, on feature phones. For those audiences, you'll need to develop a separate mobile site.Don't worry that Google will see a mobile site as duplicate content to your desktop site and penalize it in rankings, Meunier says. "If you follow Google's smartphone guidelines, you should be fine."Not sure how your current site will look on a small device screen? Last year Google released an online tool, GoMoMeter, which shows how your site looks on a mobile browser. You can also find a mobile site developer using Google's tool. For $25 a month, Mobile Moxie offers online tools for keyword research, mobile website emulation and mobile search engine simulation.3. Know When to Use Short and Long Keyword PhrasesSearchers using mobile devices often type in shorter phrases\u2014after all, who wants to tap out a long sentence on a touchscreen keyboard? On the other hand, those who use Siri, Google Now or other voice-recognition forms of search tend to use longer phrases. So how should you optimize your Web content?For now at least, many SEO experts recommend either sticking with your current keyword optimization strategies. Use shorter phrases for content that you specifically want to appeal to mobile users or for your mobile-specific site pages and using longer, "natural language" keyword phrases for content that users might be searching for using Siri or Google Now. For instance, you might want to create an FAQ page on your site with natural-language queries people are likely to speak in voice or other searches.In any event, voice search is still a tiny minority of overall search, both Fox and Meunier say. "Right now, most of the time, Siri doesn't know how to answer your question, and so it just searches the Web like you would," Fox says. "It makes search easier to do, but all the stuff that happens behind the scenes is the same."4. Do Your Keyword ResearchAs with any SEO effort, pay attention to the keywords people use to reach your site. "Notice the language they use to talk about your product or service," Fox says.\n\nFor instance, depending upon your business, you may discover a growing number of location-specific keyword terms in your site's analytics. This is typical in mobile searches, she says. You might also notice an increase in partial keyword phrases, since mobile users tend to rely even more on Google's AutoComplete feature to finish their queries.Site analytics packages are increasingly providing data on mobile search traffic, Meunier says. One example is the enterprise SEO platform BrightEdge, which has a feature that separates the mobile keywords visitors used to arrive at a site from keywords entered on the desktop.The Google AdWords Keyword Tool is also useful for brainstorming keyword phrases to attract mobile search users, Meunier adds. In "Advanced Options and Filters," there's a drop-down menu for "Show Ideas and Statistics for," which lets you filter keyword statistics by "Desktop and laptop devices" (the default choice) as well as "All mobile devices," "Mobile WAP devices" and "Mobile devices with full Internet browsers."News: Google Adds Search Traffic Alerts to its SEO ServiceMeunier also recommends Google's Webmaster Tools, which can show where you're ranking for certain keywords. 5. Make Sure You're Listed on Sites Mobile Users Tap IntoLocal business directories and review sites such as Yelp tend to rank well for local business searches, Fox says. Because many mobile searches are local in nature, it's increasingly important for local businesses to be listed in these directories and services.News: Bing, Google Deepen Social Integration in SearchAlso, review and directory sites such as Urbanspoon often have dedicated apps that smartphone and tablet owners use for conducting searches\u2014which is another reason to be listed on those sites. And when iOS device users ask Siri for help locating a local business, Apple's virtual assistant often searches on Yelp\u2014providing yet another reason to be listed there.Of course, if you get listed on Yelp, TripAdvisor or other site where customers leave reviews, it's important to continually monitor what's being said about you, Fox says. "Responding well to customer reviews, both positive and negative, is becoming more important than ever."Be Where Your Customers AreUltimately, the best strategy is to keep an eye on where technology is heading, and figure out if you need to take action. "A few years from now, it may become important to make sure your site's page can be easily transcribed into spoken words by your in-car computer system," Fox says.For now, the best mobile SEO strategy is a simple one. "Know where people are searching for you\u2014from an app, a phone, a tablet, or a desktop," Fox says. "Make sure you're there where they search for you, and that you're easily accessible no matter how people look for you."James A. Martin is an SEO and social media consultant and writes the CIO.com Martin on Mobile Apps blog. Follow him on Twitter. Follow everything from CIO.com on Twitter @CIOonline, on Facebook, and on Google +.