Paragraph two: Give three or four resons to demonstrate your opion in details while using some examples for support. 'Firstly, secondly, Finally....'
Paragraph three(optional): Descriping the other side of the theme in brief. (the other side also has some advantage, like...... but ......)
Paragraph four: Conclusion, 'In conclusion, Generally speaking, In general.....'
I took TWE twice(May 1999 and CBT Sep 2001).You can never get a score less than 4 or 4.5 with this structure, good luck!