If you were starting a new web site today, where would you start your theme? What characteristics would you demand in a theme? Why are some features required for the future? Which base them would you use? Who would you involve in the theme development? When do you need a new theme? Here are the answers based on experience with hundreds of Web sites.
When do you need a new theme?
You need to change your theme when you change your marketing material but the change need not require a new theme, just replace a few images and change the decoration supplied by the CSS in the theme.
Change your theme each time a new Web browser appears or there is a major new release of an existing Web browser. A good community developed theme with an active leader will change anything that does not work with the new Web browser. If you are using a theme that is not updated within three months, change to a more popular theme. The top Drupal themes are used on thousands of Web sites and are actively developed.
You might have to change your theme when you move from Drupal 6 to Drupal 7. Some good Drupal 6 themes have no Drupal 7 version under development. Some Drupal 6 themes have a Drupal 7 version but the Drupal 7 version is different and may have different prerequisites. Some of my Web site conversions require a new theme because the Drupal 7 version of the existing theme is overkill with potential performance problems.
If your existing theme does not support modern requirements, including RDF, RTL, and HTML5, this is a good time to update to a more modern theme.
Where do you start your theme?
Start with people. Start with the people who will sign off the final Web site and find out their requirements. They can kill your theme. They may need an introduction to modern requirements. Invole them in the process and educate them.
Look for users of the Web site. Look for people who use the Web site every day but are not technical. look for people who are about to use the Web site for the first time. Sit them down with their web browser. Ask them for their favourite Web sites. Ask them to visit Web sites using the type of themes you are considering. Some themes will be better for first time users and some for repeat users. You might find a theme that satisfies both groups.
Look for advice on themes. This page is a good start. User groups populated by theme developers will give you an idea of the problems caused by some approaches. User groups oriented to accessibility and other technology issues will help you decide the importance of RDF and some other technologies. Most user group posts are based on small numbers of people expressing strong biases based on limited experience. A lot of the posts are out of date or based on obsolete experiences. You need to find the few people actively involved in the latest approaches.
Set up lots of test Web sites. The Drupal multisite feature means you can set up a test Web site with a different theme in less than an hour. Bring the test Web sites to the people. You can make the test Web sites public and invite a huge range of people to try all your options.
What characteristics do you demand in a theme?
RDFa is required and is standard in Drupal 7. A Drupal 7 theme has to pass the RDFa information through to the Web browser or replicate the information if the theme overrides the base Drupal data.
RTL, Right To Left text, is required for some languages and is supported in the best modern themes. Arabic and Hebrew are written right to left. Some languages are written right to left when written in Arabic script. Mandarin, the written language of China, is usually left to right and can be right to left or top to bottom.
HTML5 is the new standard for HTML and provides native video display. You want HTML5 for 2012 onwards with an option to present video using older techniques for older browsers.
Why are some features required for the future?
RDFa is used only by some rare search facilities. One day soon Google will launch extensive RDFa support and the winning web sites will be the ones ready with RDFa.
HTML5 video is required because all the alternatives have severe problems.
If you present your users with an option to build there own pages or a blog, you want options to let the users change the page colours and images. Some Drupal 6 themes have the flexibility built in. Some Drupal themes gained the colour facility during the rewrite to Drupal 7 and may now be a better choice for your Web site.
The theme must validate as accessible. There is a wider range of Drupal 7 themes validated for accessibility.
You need versions of the theme, or compatible themes, for all the smartphones including Android, Blackberry, and the iPhone6. (The iPhone 6 will be announced the day after you buy the iPhone5.)