Turnitin.com looks for quotes taken directly from web pages - ie plagiarism.
So the only true way to 'beat' it is to do complete the work yourself and without direct reference to any online material.
I guess thats not the answer you were looking for though.
If you are having the said homework completed by our homework experts here (obviously as an example you could work from), you would put your question in the title and in the details ask the expert to deliver it to you in a file. That way the content is not directly searchable from the web. As the content would be the experts original work and is non searchable from the internet then turnitin would not be able to detect it as plagiarism.
Hope that helps,