My first comments to you
The best system has appeared to be that you send me your article. I read it quickly and give some major comments that come to my mind easily. Thereafter, you can decide if you continue with our service, and we can flexibly help you in the ways you like.
The usual case is that I first read the article and give some major comments to improve the article. This is by no means the language at the sentence, paragraph or even article level. The first thing that I often see in the articles I get to edit is that the authors have not told their story in such a way that a reader can easily follow it. So, many times, my first comments are something like: Write about this and do not write about that here.
For a couple of first rounds, my service it is not editing at all. It is commenting the article at the research level. My help to you is to present criticism so that you notice certain things you have not written or presented so well. I criticize but I always also try to suggest practical advice on how you could improve the article. If I do not exactly know what to suggest, the discussions have always helped the author to go on and continue writing.