Quoting: Dougm1966
My suggestion would be to take each case individually and charge by the hour. You just never know how bad or good the English will really be ... or long it will take to do.
The thing is that it is fine if you charge by the hour if you are doing a few pages here and there, but this is my full time job and I proofread over 1500 pages per month and in most if not all cases proofreaders will charge by the page.
And there is a more important factor in the equation that most proofreaders work form home and have clients all over Poland, along with the fact I have clients all over Europe; so its a wonderful idea sitting next to a beautiful girl going over her works (sorry, going over her work), but I am afraid time and distance and wife would not allow it. :O)