How can I improve my reading comprehension? For my Ged Test?

Hello I live in stockton, Ca and im going to take my Ged language arts reading. And I need a good score to p. I have read the Ged book already but not quite Got a good score. so what cles in stockton or How can I improve my reading comprehension so I can understand exactly what Im reading, Because when I read I have to read it once or twice or three times in order to understand a sentence. so please help me, Im having trouble comprehending what I read in pages and short story's. your answers would be greatly appreciated. Thank you