This is a common problem. You have a lot of ideas but they do not seem to relate to the question. Before you start to gather material for the essay topic, pause and look more closely at the words in the question.

You have to know WHAT the question is asking you to write about and HOW you are going to write it. Are you writing an argumentative essay or a critical review or a reflective essay? Reading the essay question in this way will give you a focus for your research. Understanding the meaning of words like describe, critically discuss and review will ensure that you have used the appropriate writing style and language for the essay.

Select the Planning the essay skill to learn and practise some strategies for reading the question, planning and organising the essay.

All academic essays have a particular structure. You may already be familiar with the basic three-part structure: introduction, body, and conclusion. Each part has a specific purpose and must be structured accordingly. Each part must be linked to the next to ensure the whole essay flows smoothly and ideas are developed logically.

Select the Building the essay skill to learn how to write effective introductions and conclusions, and build ideas logically and with relevant evidence. 

Select the Achieving coherence skill and learn how to achieve unity and coherence within the paragraph and throughout the essay.

At university, you have to write different types of reports and essays: expository, argumentative, discussion and critical reviews. You need to understand the characteristic language features of each essay type, so that you can deliver the answer in the appropriate format and style.

Select the Understanding essay types skill to read some sample essays for examples of essay structure and the specific features that relate to each essay type. 

If English is your additional language, you may need to review aspects of English grammar and sentence structure that are different from your first language. You need to understand the behaviour of words in English when used as a noun, verb, adverb or adjective. At university, you need to demonstrate the ability to use a wide range of sentences and vocabulary with good control.

Increase the accuracy and clarity of your written expression. Know what to look for and learn to proofread your own writing. Go to the Checking the essay skill and select the tab Editing for some practice at noticing and correcting basic grammatical errors.

Acknowledging the sources of your research is an important convention of university writing. Go to Checking the essay and select the tab Academic style to learn some important referencing conventions, including some example of how to use quotations and summarise or paraphrase other people's ideas to get you started.