Many successful writers offer the same and simple advice to new writers: read a lot and write a lot.
It isn’t just the act of reading that is important though. To make that reading time as effective as possible, you need to read and reflect on what authors are doing well. This will help you become a better writer.
Furthermore, you want to read everything in your genre. You need to know what your readers will have read as well. You need to be a fan first.
If you want to write a book of science fiction for middle grade readers, then you should read every popular middle grade sci-fi book available plus some that aren’t so popular.
I just finished reading Neil Gaiman’s collection of nonfiction writing in his book, The View from the Cheap Seats. Like a lot of author authors, he can be found giving the standard advice to read a lot and write a lot.
As you read Gaiman’s personal stories about his love for books as a young boy and his love for books as an adult in his many forewords and introductions to other books and his writing about friends and colleagues, you realize that the advice to “read a lot” is more than token wisdom.
He lived it.
He claimed to have been practically raised by librarians. He mentions casually and anecdotally evidence of a reading a long history of fantasy, science fiction, and comic books.
He wasn’t just an avid reader; he was immersed in his genre. He was aware of the history of each genre he wrote in and because of that he could write something new and unique and yet still able to fit in a genre that readers knew well.