An opinion essay should consist of:
- an introduntion, in which you introduce the subject and state your opinion clearly
- a main body, consisting of two or more paragraphs (each presenting a separate viewpoint+example to support it); opposing viewpoint supported by reasons/examples
- a conclusion, in which you restate your opinion using different words
Model Essay

General Scheme
(1) These days ... + ... Some people believe/argue that ... I tend to agree/disagree with this opinion and in this essay I will support my view with examples.
(2) Firstly, ... For example, ... In other words, ... then I believe that ...
(3) Another reason why I agree/diagree with ... is that ... Take ... as an example. + ... I strongly believe that ... What is more, ...
(4-alternative opinion) On the other hand, ... As a result, ...
(5) In conclusion, although it is a common believe that ..., I believe that ... Personally, I think ...
See more ways on how to express your opinion here.