...reflection on my mid-term paper

I was really impressed when my teacher Sarah gave me the evaluation grid with her comments on my mid-term paper. I know I spent some time reflecting on my learning process and I tried to give my best while writing it, but I couldn’t imagine somebody would think it was “excellent”.
I went through it and I noticed that there were few errors but a lot of things I could have written in a better way. As the teacher pointed out, my style was quite informal. I’m aware of this, because I wasn’t expected to write it like it was a formal essay. At the same time, I’m aware that I often tend to write things down informally, so this is something I need to improve. I noticed some mistakes about punctuation (especially commas) and some related to vocabulary.
Two comments were identical: they said that it’s not good to start a new paragraph with a linking word that strong links to the previous sentences, because it indicates that I was continuing on with the same idea, instead of proving my will to start a new paragraph.