3 months is not much for prepare for the TOEFL, but don't worry becuz the important thing is how high do u want/need in the Test ?
U both should go to a class for being trained with the skills and tips of taking TOEFL and study on your own with books. Some TOEFL books r very useful such as Longman, Peterson, Arco ...
For more information for TOEFL please visit http://www.toefl.org
to get newest information. By the way, in some few years, the Test is going to be change a bit in the style and content.
If u describe or post here more details about what troubles u, many good guys and girls will help u.