Hello, I was in same condition like you and scored 6.5, but last month I scored band 7 in writing, even though I made many mistakes. The main tip to score high is structure of writing depending on the essay type. I would recommend you to read from ieltsadvantage.com and follow the format provided there. You would definitely score 7 or more, as I have seen your writing is very good, just missing appropriate structure. Although your intro and conclusion is written upto the mark. Your paragraphs are little lenghty and missing example. If you will follow the structure given on that site, will guarantee that you can score 7-7.5 according to your present writing.
Actually, there is nothing wrong in your writing, but examiners look for particular approach. I was confused about it too that which format to follow. Now, after using it myself in exam, can recommend you with surety.
Lastly use on the other hand instead of on top of
Tips what I can suggest:
Use appropriate synonyms throughout essay
Use only complex sentences
Avoid passive voice
Don't use words like very, big etc.
Use formal words
Each body paragraph must have one idea
Plan 3-4 minutes about structure before starting and 3-4 minutes to review. So practice to write essay witin 32 minutes
Task 2 has more bands than task 1. So,write task 2 first.(task2 - 6 bands and task1 -3 bands)
