I averaged a 38 on my practices.. I don't map any of my passages - I think thats a confusing waste of time.
For verbal, I have an okay score of 10-12 on my tests. There are two types of questions: specific and general quesitons. Specific quesitons require specific knowledge of passage details. General questions are inferences or themes from the big picture/meaning of the passage.
So I start by prereading the questions and marking (in my head) questions that require me to "plug and chug" passage information so I can highlight that information or find it in the passage during my first read through (eg a question such as "the author provides the most support for which of the following" requires you to search out each of the following and mark them. A questions such as "the passage mentions all of the following except: I. Beans II. Rice III. Carrots" will require me to be on the look out for the words beans/rice/carrots). At the end all the question stems usually have the same theme to them, so I don't necessarily have to memorize 2-3 questions, just 2-3 key concepts to look out for and highlight. Then I read the entir epassage quickly for MEANING. Along the way I might stopg or going slowly to answer the questions I marked, or just highlight the key things I was on the look out for. Now, having finished the passage in one read, I can easily answer the big picture questions, and I know where the important specific things are in the passage, so I can easily find them and go back to them.
For bio, I just read for meaning. If you understand what they're trying to say and the experiment, then it shouldn't be too hard. I think practice makes perfect - I've done over 100 verbal passages (timed) and taken all the FLs twice, and I can definitely say that my memory and ease of understanding has gone up a lot. It's all practice. I started out getting 8's on my BS, now I'm getting 12-14's.
Orgo is all mechanisms - if you know mechanisms, you don't need to know anything else. All orgo passages come down to "what is going on in this reaction" and figuring out where electrons are being pushed, then answering the questions from that. My friend got a 15 on BS and he said he never reads orgo passage, he just looks at mechanisms. I'm more or less the same, although I do read the words just to get an idea of whats going on in case theres a "context" question.
For PS, again I just read the passage and answer the problems. If you know your concepts well, you should be able to easily figure out "whats going on" and the "big picture" and "meaning" of the passage. Usually they describe some sort of mechanism or some application of a basic concept you should already know well (titrations, redox reactoins, etc).