The goal of the editing process is a text that is correctly understood and does not attract criticism of its language from the editors or referees. On the other hand, what is certainly not the goal is to polish the manuscript to a state of literary perfection. With a certain amount of experience and maturity as an editor, it is possible to concentrate on things that really make a difference to the function of the text, and to leave other things alone. I’d say I have this level of experience by now. That allows me to offer a service which reliably ensures that the corrected manuscript is fit for purpose but for a mid-range price.
If you look around the market, you will find some editing services that are much cheaper and some that cost about double my usual prices. The latter may include, for example, back-to-back correction by two different subject experts. That probably does achieve some improvement. If you wish, I can organize this for your manuscript. But I believe that most of the time, that is not really necessary; and I know that my normal prices already stretch the available budgets of many academic researchers.
Editing can be done in a more rational way with some knowledge of the linguistic issues involved. Everyone knows that grammar and syntax are different in English than in German. What may be less well understood is that these differences have an effect on the way we need to structure paragraphs, so that readers experience the text as coherent and understandable. This is an aspect where a native speaker with editing experience can make real improvements.
As experts in a field, when we write something we usually concentrate, to the point of fixation, on describing the matter exactly as we understand it – which is, of course, a step ahead of the others. But the measure of every text is how well it works when people read it. It should accurately anticipate their existing knowledge, their expectations as to what makes a good argument and whatever critical attitude they may have towards the subject. Remember that even when writing for a specialist journal, the audience is still significantly wider than your own group. Here lies a major benefit of outside editing: an editor who is less familiar with the subject matter than you are is positioned to spot any obstacles to understanding your message.
When you are preparing a manuscript for a specific journal, you should always read the journal’s Instructions to Authors and make sure the manuscript complies with them. Some journals have much more detailed instructions than others. Remember that journal editors judge an article not just by its content but also by how much work it will take to get into shape.
I usually presume you have done your homework in this regard. Of course I can look after this area on request, but it is extra work and will cost extra. What I do watch out for is consistency. Taking abbreviations as an example: I check that the list of abbreviations is complete and that you always use the abbreviation once it has been defined. My guess is that things like this are the most irritating for desk editors, because they are hidden errors that they have to find.
It is good to know whether the journal expects British or American English. This does not affect the language in general (which has virtually no differences in a formal scientific text) but it is relevant to the spelling of certain words and sometimes to the choice of terminological variants.