I am a native English speaker as it is the official language in my country and the language of instruction that I have used throughout my education.
I am a writer, editor and proofreader and pride myself on being conscientious when proof reading. I am familiar with the peculiarities of both American and UK English, the syntax, grammar and semantics. While what you requested for is proofreading, I will also make sure to work on clarity, regularisation of tone and nuance in this project.
I recently joined the Society for Book and Magazine Editors of Nigeria (SBMEN) because of my dedication to this craft.
This is how I will go about working on your document.
1. I will read through to familiarise myself with the message and tone of the document. This will help me to know how to bring the important points to the fore without wasting words or rambling.
2. I will start reading again and make corrections in spellings, grammar errors, semantics problems, etc. These will all be marked up so you can see the exact changes made in the document. I will do this twice, with a break in between so that I come back to the document with fresh eyes.
3. I will save and have two copies: the edited copy showing all the changes I made with notes and the clean copy showing your error-free document.
4. I will run a final check on the clean copy by reading it out loud, twice. This always helps in picking out words that do not jibe or that are just plain odd.