The LSAT provides passages, not necessarily essays
The material in the LSAT Reading Comprehension sections contain passages that are adapted from sections from books, journals, and other sources. These passages may or may not be complete essays, and thus, may or may not have clear introductions and/or conclusions. Indeed, the passage may have been adapted from the middle portion of a source. LSAT test-takers often incorrectly assume that the material provided is, in fact, a complete essay, and will thus assume that a clear thesis statement will appear in the first paragraph, and will then only read the first paragraph and then jump to the questions with insufficient information. Yet many question types -- main point questions in particular -- will provide incorrect choices that appear attractive if one has only read the first paragraph. Likewise, you may encounter questions that ask about the function of the final paragraph, and, incorrect choices will state that the final paragraph is a summary or conclusion, when, in fact, it is not.
Sharpen your reading skills
If you're uncomfortable with the formal and academic material found on the LSAT Reading Comprehension section, you may wish to sharpen your skills by reading some of the material that the LSAT passages are adapted from. The style in these passages will likely be similar to the style found in the LSAT's adaptations. (Note: remember that you are reading to familiarize yourself with style, not necessarily trying to learn the material.) You may easily find formal, academic material to sharpen your reading skills by looking at the back of any LSAT PrepTest for citations. For example, citations from LSAT PrepTest 46 include "What is Prosperity?" authored by William Bryant Logan (© 1995 by POINT), and "Music of the Hemispheres." authored by James Shreeve (© 1996 by Discover).
Use different reading speeds
Consider three different reading speeds -- textbook, magazine, and skim. Textbook speed is the speed at which you would read dense, difficult material such as technical, scientific, or philosophical material. In this speed, you read slowly and carefully to ensure that you fully understand each detail and how those details interrelate. Magazine speed is the speed at which you would read casual material for pleasure, such as magazines, novels, and newspapers. Clearly, you never want to read at this speed for the LSAT. Finally, skim speed is the speed at which you would glance over material to get a basic idea of the main point, purpose, and author's opinion, but would not delve into details.
The problem that many test-takers have is that they only utilize textbook or skim speed. By only using textbook speed, a test-taker will spend far too much time on details that the LSAT never even asks questions on, and thus the test-taker will complete fewer passages and questions. On the other hand, by only using skim speed, a test-taker will only get superficial knowledge, and, although s/he might be able to do main point questions, will have great difficulty with questions that ask about details. Or, by using skim speed, a test-taker might get a rough idea about content and then guess as to the rest. However, guessing content is an enormously bad idea because the LSAT may provide content that goes against what one typically reads in university courses. For example, in university courses you may have often read of women who have consciously broken the mold of a male-dominated profession or tradition. Yet, the content of the second passage of LSAT PrepTest 48 is of a woman who "embraces" a tradition characterized by male poets, and the author endorses this embrace. No shortage of incorrect choices appear for those who guess that the content is about a woman who broke free of a male-dominated tradition, or that the author criticizes a woman who accepted a male-dominated tradition. See Question 7, choices, (A) and (C); Question 8, choices (A) and (E); and Question 12, choices (A) and (B). Another skimming technique to avoid is to only read the first sentence of each paragraph on the belief that the first sentence is necessarily a topic sentence, when, in fact, it isn't. See LSAT PrepTest 48, Section 3, Question 27, (E).
Instead of doing only skimming or textbook speeds, learn to be able to shift between the two. For instance, suppose that you encounter a difficult paragraph that describes a general situation. If you are good at dealing with general language, you could shift into textbook speed and churn through the details to gain comprehension. After that paragraph, though, you may very well encounter a paragraph that contains an example of that situation. If so, you could then shift into skim speed and remember that if a question asks about the example, then you could simply return for details. Conversely, if you are poor at dealing with general language, but good at understanding specifics, you may wish to go skim speed through the first paragraph, and then read the example in textbook speed so that you understand from that specific situation what the general situation is. Consider the second passage of LSAT PrepTest 49, Section 3. The first two paragraphs discuss "centers of style" for African art. The third paragraph opens with "One such center...", which is a clear introduction to an example. If you understood the first two paragraphs well, then you could easily skim through the third paragraph, and, if questions appear asking about the example, as in Questions 9 and 12, then return to read those details, but, for Question 9, you could still skim through the paragraph to retrieve the necessary detail, which clearly appears in the second sentence.