What are the best ways of testing web applications when you have to perform cross browser testing?

There are many tools and websites available to support cross-browser testing such as: IE Tester, BrowserShots, and CrossBrowserTesting.
Check this link that contains other tools and websites for this purpose: http://www.1stwebdesigner.com/design/tools-browser-compatibility-check/

I am useing Oracle Virtual Machine

Testing???