There are a number of common features that you can use across your styles for various mobile platforms.
If you don't have a mobile device to test your Joomla! template on, there are a number of online simulators for mobile browsers. One of the more popular mobile browsers is Opera Mini (http://www.operamini.com). The Opera Mini simulator is available online at http://www.opera.com/mobile/demo/.
Once you have read and accepted the End User License Agreement (EULA), you're free to type the address of your Joomla! website into the address bar provided.
Note
Note that you will need Java installed to use the Opera Mini simulator, which you can get at http://www.java.com/en/download/index.jsp.