Critical essays  are generally defined as the personal opinion of a writer. Critical essay  can be about anything that you see around yourself. 

You just need a  proper assessment of the topic and then evaluating it.
Don’t forget to mention  the reference sources in your essay as it will help you in assessing it  afterwards.
Here we will be discussing some do’s and don’ts of writing  any critical essay. 
Do’s  of Writing a Critical Essay
The important things that you should remember while writing any critical essay  are: 
Essay  should be easy to read
You should frame smaller sentences and paragraphs while writing critical essays  because it will help the reader to understand your point and arguments clearly.  The key points and arguments including examples should be visible to the reader  at one glance.
Introduction  of Overview in Essay
Do mention the thesis of your subject in starting of your essay as it will help  the reader to understand the motive behind your writing. As it will completely  be based on your thoughts, therefore it is necessary to make the reader  understand the motive behind your subject.
Use of  Examples
An example helps in understanding the topic to a great extent. Also you can  mention any alternate options supporting your subject with the help of  examples. Examples are the base of your arguments in any critical essay.
Use of  Advance Vocabulary
Only the knowledge about the topic is not necessary sometimes. But while  writing critical essays, your command over the language with the help of  appropriate grammar and vocabulary should be showcased to the readers.
Don’ts of Writing a Critical  Essay
The important  things that you should avoid while writing any critical essay are:
Typing  errors should not ruin your Essay  
Make sure that  any typos don’t ruin the motive behind writing an essay. It leaves a bad  impression on the reader. So you should be careful in writing any critical  essay.
Structure  should be aligned
The message that  you want to convey through your critical essay should not be misaligned at any  point in the essay because the reader will lose his/her interest in reading  your essay.
Avoid  Negative language
You should  always remain optimistic in telling every point in the essay. Readers will  definitely appreciate your approach towards that subject in that case.