I have a reader in Australia (Hi Dave!) who is working on a website for his language school. He got it up but he isn’t really happy with the theme he chose. He wrote and asked me about the best method for trying out a new theme to see how it would work when you have a live site that you don’t want to “mess-up”.
For those in a similar situation as Dave, I recommend creating a test site on a sub-directory of your live site. If your live site is on your “root” directory, you would set up an installation of WordPress, for your test site, on a sub-directory and it would look like this: http://mysitename.com/mytestsite.
You can go to your web host and simply do a one-step install to set up a new installation of WordPress on the sub-directory. Once installed, go to the dashboard of the live site and navigate to “Tools,” then to “Export ” to export an .xml file of your site content. Then go to “Tools” on your test site and “Import” the .xml file into the test site.
This will bring over all of your existing pages and posts and images into the test site. You will have to start customizing the site over again, including setting up your Nav Menu and Side Bar Widgets. Also make sure your “Permalinks” (under “Settings”) are set up correctly. I favor http://yoururl.com/the-post-name, unless you have a really good reason to use a different permalink.
Alternatively, if you have a more complex, mature site, you could make a complete “mirror” site on a sub-directory using a plugin like BackupBuddy. The test site will then look identical to the existing site. Then you can change the theme and work on customizing the new theme to the look you want.
When you are finished and you like the result on the test site, you can do one of two things. If you don’t have many changes, then you can make the same changes now to the live site. If your site required quite a bit of customization, then you might want to do another backup with BackupBuddy and overwrite the live site with the newly customized test site.
It is always great to have a test site to play around with changes before you try them on your production site. If you keep the test site live, then make sure you keep the plugins and versions updated just like you do on the live site, otherwise the test site could get hacked. Since it is on the same hosting account as your live site the hackers can jump right over and get your live site too.