Give yourself time. If you do the reading in haste, it will be difficult to retain anything. You need to give yourself time; you should budget two to three hours for the reading each week. If you want, you can consider the reading each week as being something like "going to class," but instead of listening to a professor lecture, you are reading and taking notes instead.
Read; don't skim. If you try to skim the reading, it will not work. Stories are not like the kind of writing you might find in a textbook or article. You cannot skim for the "main idea," reading the topic sentence of each paragraph. Instead, you need to read each sentence carefully, keeping track of the characters and the plot sentence by sentence.
Focus on the reading. You need to shut down other applications on your computer while you do the reading. If you focus on the reading without distractions, you will be able to read more efficiently. If you constantly interrupt the reading, it will take you much longer to finish the work and you will retain much less.
Read out loud. The best way to slow yourself down and make sure you retain the content is to read out loud. The reading each week consists of appx. 15,000 words which would take you approximately 90 minutes to read out loud. For some of the readings, there are free audiobook versions available so that instead of reading out loud, you can listen to someone else read to you.
Take notes as you read. As you finish each story, be sure to record a few sentences in your Reading Diary post right away, especially if you suspect the story might be one of your favorites. You need to take notes while you are reading if at all possible.
Read the introductory notes. Read the introduction to the unit as a whole before you get started, and also make sure you read the introductory notes at the top of each story. These notes can be especially useful if there are unusual words that come up in the story that you might not recognize on your own.
Use a dictionary. You need to make sure to look up words you do not understand. You might have a dictionary look-up system that you like to use on your computer, and you can also use a browser look-up. With Google, for example, you can type "define" and then add the word you want to look up in a dictionary. For example: define autochthonous.