Many thanks for putting your essays in this thread. Without any doubt, your essays are useful. You write effectively and interestingly. I really enjoy reading your essays.
About three years ago-for IELTS preparation-I had four courses in an institute in Tehran; concerning four skills: listening, speaking, reading and writing. The courses were really useful. They made my language skills improve significantly, and consequently I scored an average 7.5 out of 9 in IELTS exam. I scored 8 out of 9 in writing module.
I am not going to give you some tips in this public place, since it may affect your morale negatively, or even may hurt your feeling. However, there are some rules in essay writing which should be followed(va man heyfam miyad nagam). Following those rules will cause you to increase your writing band in exams.
For example, it is important to have a Five-Paragraph essay format. This format is so common both in TOEFL and IELTS. In this format the first paragraph is used for introducing(introduction). You should rephrase the topic in this paragraph and make it seem more interesting for readers to get interested in reading the essay. If the topic question is about your personal opinion about something, you should also give your opinion clearly(agree or disagree) in this paragraph and make the readers know the supporting reasons you are going to give in the next paragraphs. You ought to have three reasons for your idea. Those three reasons will be discussed in more details with other supporting sentences in three independent paragraphs.
In the second paragraph, you should write about your first reasons. The first sentence of this paragraph is made from your first reason and it is the topic sentence of paragraph. You have to write some sentences about the first reason; trying to support it with some evidence, examples, or some logical statements.
In the third and fourth paragraph, you should write about the second reason(mentioned in the first paragraph) and the third reason(mentioned in the first paragraph) respectively.
Finally, in the last paragraph, you should again write a sentence with different words about your three reasons which you have mentioned in the first paragraph. The key words of this sentence are your three reasons, but the words are different(noun, adjective, verb which can be made by the root of words e.g. improving, improvement, improved, ..). You shouldn't directly disagree or agree with the main question of topic again. It is done indirectly.
Among three paragraphs, you should obviously use linking phrases such as, in addition to that, firstly, secondly, finally, In the first place,..
When the topic is asking about advantages and disadvantages of something, you shouldn't write your opinion in the first paragraph. If you believe the advantages are more than the disadvantages, you should first write one paragraph about disadvantages, and two paragraphs about disadvantages. In this case, the conclusion paragraph(the last one) is always close to the side you are supporting. Plus, in this case, you have to give your idea directly in the last paragraph by proper sentences such as, 'In my opinion, the advantages of ..weigh its disadvantages....'.
I hope it helps.
I am in a hurry. Alas I have no time to check this post to correct my mistakes. I have to leave my office quickly. Sorry for mistakes. If you need more explanation, just let me know.
All the best,
Behnam, 10 October, 2012