Your goal with your mobile website is to create a peak user experience to your mobile base — getting them the information they need quickly and easily. If you do decide to create a mobile-only version of your website, here are a few things you’ll need to do:

1. Select a URL for the mobile site
There are four generally accepted conventions for the name of the mobile version of your site:
A) Get a top-level domain, unique from your current domain name, e.g., www.yoursite-mobile.com or www.m-yoursite.com or www.yoursite-togo.com
B) Create a custom subdomain to your current domain, e.g., www.mobile.yoursite.com or www.m.yoursite.com
C) Add a folder to your current domain, e.g., www.yoursite.com/mobile (this is the easiest option)
D) Get a .mobi top-level domain, e.g., www.yoursite.mobi

2. Include only the most relevant information on your mobile-only site.
A mobile version should include a subset of the information from your site. Include small bits of information that users can read in a short amount of time, e.g., while on a bus, in a taxi, or waiting for an appointment. You can include links to longer documents and large images on your regular site, but don’t include them on the mobile version.

3. Create a way to get to the mobile version, and a way to get back
Some visitors don’t like being served up a “stripped-down” version of your site and would rather have access to all the information contained in your real site. Detect whether someone’s visiting your site from a handheld device and redirect them to your mobile version. Once there, provide a clearly visible link to view the regular site in case someone wants more information than you provide on your mobile site.

4. Keep the navigation and page structure simple
Include only the navigation items that mobile users are likely to want, and keep it all in one column. You might want to have links to all information on the mobile site available on the home page so users don’t have to click deeply into your site. If you’ve kept the content on the mobile version streamlined, this list of navigation choices shouldn’t be unreasonably long.

Once you’ve created your mobile-only version of your site, be sure to test it on as many handhelds as you can. If you’ve done your job correctly, you’ll have created a site with a nice balance of functionality and content optimized for your mobile users.

The goal of “One Web” is to create, as far as is reasonable, a comparable web user experience regardless of which platform a visitor uses. This doesn’t mean the content must be identical on desktops and handhelds – content can be adapted for mobile devices. There are some cases where you may want to narrow the features and focus on specific things users do when they’re on their smartphones, as opposed to when they’re on their desktop computers.

So, when is it better to create a separate, optimized, mobile-only version for your website?

If you determine that your users can’t or don’t want to use all the information contained on your site, or there’s some specific information that mobile users would be more likely to want, you should consider creating a version of your site created just for handheld devices. Here are a few cases when your website is a perfect candidate:

1. Your users need specific information…now!

If your site is a destination for travelers (airline passengers, rail commuters, people driving somewhere) they may be searching for a small bit of important information (a gate change, a train schedule, a map). They probably aren’t looking to read lengthy reference material, look at rich images, or interact with a Flash module. In this case, the mobile version of your site can serve up just the information this type of customer wants, with the rest of your company information on the full version of your site.

2. Your website is data-heavy.

Accessing data on handhelds can be very slow on low-bandwidth mobile networks. And, it can be expensive if your customers are charged according to the amount of data they send and receive. If your site features lots of images, graphics, or Flash it might be best to create a “lite” version of your site for mobile viewers, without all the bells and whistles.

3. Getting your site to work on mobile devices is too hard.

If your site wasn’t coded right the first time, getting it to work on today’s range of mobile browsers might entail too much work. In this case, you could start fresh and create a stripped-down version of your site to work on mobile devices. Of course, a better course would be to re-do your whole site using web standards and keep mobile considerations in mind.

If none of the above apply to your website, you probably can get away with one version for desktop and web devices. Just make sure you test your site in as many browsers on as many devices as possible.

P.S. Just a few stats on mobile use from Marketing Sherpa:

• 31.9% of all mobile subscribers used a Web browser on a mobile device in the three months ending in May 2010, according to comScore. That’s up from 26% in comScore’s September 2009 three-month average.
• 30% downloaded a mobile app in the three months ending in May, compared to 6.7% in the September 2009 three-month average, according to comScore.

It’s no surprise that Nielsen shows a dramatic increase of 36% in the number of mobile internet users worldwide over that past year. What may be surprising is that 14% of this group view sites exclusively on a handheld device, not on a desktop or laptop computer. As the number of mobile-only surfers grows, and mobile computing becomes a part of the daily routine, it will become more and more important to make sure your site provides a good user experience for everyone, no matter how visitors access your website.

So, how is developing a website for mobile devices different from developing a site for desktop computers?
If you’re using good web development practices, your adjustments should be minor. We’ll assume you’re already using web standards, optimizing your images for the web, creating an organized site with simple navigation, and providing clean copy for your visitors. Keep the three following ideas in mind and you’ll be well on your way.

1. Keep it simpler.
With slow download speeds on some mobile devices, you need to keep it small. Provide minimal navigation at the top of the page, limit use of large images, and provide a text equivalent for each image. Serve up information in small pieces over a series of pages. And, don’t have an auto refresh or anything that requires repeated downloads from the network.

2. Design with device limitations in mind.
Make sure your website doesn’t use any of the known hazards of mobile devices. Limit scrolling to one direction, don’t rely on fonts or colors as a way to distinguish between elements, don’t depend on cookies, make sure the site works well with or without CSS, don’t use pop ups, and avoid Flash and JavaScript.

3. Design with device capabilities in mind
Mobile devices do some things better than desktops  and laptops. For example, you can customize your site for mobile phones by making phone numbers dial when clicked.  Or, you might want to include capabilities to send and receive MMS and SMS messages on your site.

Test your site on as many devices as you can.
There is an ever-growing number of smartphone operating systems, each with its own web browser: The biggies today are Symbian, Blackberry, Windows Mobile, Linux, iPhone, PalmOS, and the recently released Android OS. While you can run your code through a validator and check your site with online emulators, there’s no substitute for testing your site on actual handheld devices.

If you don’t have 6-7 extra smartphones lying around, don’t be shy—ask your friends to let you take a peek at your site on their phones. If you’ve done your job right and followed the three steps above, it should look awesome!

If you want more information, take a look at the the Mobile Web Best Practices 1.0 guidelines, developed this year by the W3C, the international organization that develops standards for the web.