Rewrite your draft in a professional writing style where necessary. See the tips in the next section.
Read your own text aloud. This way you can hear whether there are language or spelling errors, and whether there are unclear sentences that need to be rewritten.
Use a language and spell checker
Print your text, so you can easily check it. Moreover, because of the different format, you will likely notice different issues.
Have your text read by somebody else. A second reader who does not yet know your text will easily notice if the text is missing information, is not logically ordered, or if it contains spelling mistakes.
Leave your text for a few days. This way you can look at your report with fresh eyes again, and you will notice errors that you previously overlooked.