There isn't a single author I can recommend because I don't know what you need to work on.
You could try an intensive reading method. Find a book that is easy for you to read (a children's book, for example). Try to read it as quickly as possible and write a paragraph or page-long summary of it. Ask your tutor to make sure it makes sense and rewrite it if it's incorrect. Include a list of unknown words and jot down confusing sentences/parts and work on them with your tutor as well - be sure to try to use those words and grammars as often as possible.
Keep reading books, slowly increasing the length and complexity over the span of about three months.
