I charge $8 per standard page I type up. A standard page is approximately 285 words (avg) and 300 (max), Times New Roman 12 pt font and double spaced. Things like title pages, abstract pages, and bibliography pages are free. Payment is always 100% in full in advance. I don't even put anything on my calendar, let alone start working on it, until it's paid. PayPal is the method of payment I accept.
If I make a mistake in following your original specifications, the fix is free and I will do it ASAP (usually the same day you tell me about it). If you decide after the fact that you would like other changes, I will give you a fair price for that additional work but it is never included in your original price.