If you have a command of the English language, there is always a temptation to produce the text yourself in English.
But what about the most effective use of your time? Perhaps you should first record your thoughts in clear German and then use Machine Translation (MT) or ask a translator?
Machine Translation has recently made enormous progress through the use of Artificial Intelligence: the results are not even comparable with those of a year ago.
But you may be worried that the machine did not understand you correctly for once: wouldn’t proofreading by a native speaker who understands the subject matter be the best solution? I can take the worry about the quality of the English off your mind, leaving you with one worry less.
With this kind of work I charge for my time, based on the actual hours spent. I will however give you an estimated figure before I start.