1. First, you must master all the grammar rules so you'll avoid making any grammar mistake when you're writing essays and postcards as well!
2. Come out as many ideas that you can to make your writing more interesting and make the essay longer .

3.You are suggested to insert some idioms, your feeling about the essay topic and your hope about the topic 

4. Introduction and ending are very COMPULSORY

that's all from me.  I hope you can write your essay much better in the future bye!