It's a bit meta to write about what kind of writer you think you are, but I'm going to try it anyways. In my spare time I play in a punk/emo band, for which I write all of the lyrics. When I reflect on how I prepare for this I first do this mentally, meaning I take enough time in my head to come up with the right words, structure and phrasing.
This method I also apply when I write on a more professional level, like for example papers, job applications, personal statements etc. I always try to come up with an idea and writing approach in my head, followed by writing everything at once. I don't know whether this is the right approach, but I feel like this has always been the right approach for me. The only downside of this all is that I tend to procrastinate.
Proofreading however, I don't take for granted. I try to reread my written texts with great care and usually find some mistakes I didn't notice when initially writing it. When another persons corrects my texts they usually find mistaked I even couldn't find when proofreading it myself.

