Paragraphing and Logical Organization
Two aspects of coherence and cohesion are your use of paragraphing and logical organization.
The easiest way to get this right is to follow the paragraph structure that you're given by your IELTS tutor. Following those structures will allow you to organize your essay into suitable paragraphs and include logical organization because you know exactly where to put all the information in each part of your essay.
Something else that the examiner is looking for when deciding on your coherence and cohesion score is logical organization of ideas and progression. The easiest thing you can do to get this right is to plan your essay before you write it. If you've written an essay plan, you know what your ideas are and how you're going to develop each of those ideas. Then, you have a map of what you're going to do in your essay. As long as all of your ideas are appropriate and the development is related to the idea you said you would discuss, you're going to get this right. By writing an essay plan, you can ensure that this part of your coherence and cohesion score is appropriate.
Referencing and Substitution
The next area is referencing and substitution. Referencing and substitution really depend on your language ability. If you have a good level of English, you're probably doing this correctly already. Let me explain what referencing and substitution mean so that you know if this is an area you're doing correctly or need to work on to improve your coherence and cohesion score.