You need to adopt different approaches for different passages.
These are as follows:

Read Passage –> Answer Questions:

This is the traditional way or reading the passage first and then approaching the questions.

Answer Questions -> Read Passage –> Answer Questions:

This approach most commonly used is to have a look at the questions first and then read the passage, underlining part of the passage where an answer to the questions read may be found. After reading the passage, one can go to the questions and if need be just revisit the underlined part. However, while one is reading the questions, one must not waste a lot of time reading any inference-based questions and just keep a look out for names, events and terms that can be found in the passage.

Answer Questions -> Read Passage -> Answer Questions -> Read Passage:

In this approach, one never ends up reading the passage. A question is taken one at a time and its answer is searched for in the passage. Obviously not many inference-based questions can be answered in this way, so these questions will have to be left. But if it were a fact-based passage, these types of questions would be minimal. Also one can take advantage that usually the answers to the questions would lie sequentially in the passage.

You could also follow this approach. Around one-third of the passage is read, which gives one a fair idea of the structure of the passage. Then questions are looked at and all those questions whose answers lie in the part of passage read are attempted. Then for the remaining passage the same approach is followed. This also helps in saving time searching for the answers as the amount of passage unread is less and also one understands the flow of the passage. A few inferential questions can also be answered using this approach.

The above approaches coupled with a proper selection of the passages to be attempted should help one comfortably clear the cut-offs of the Reading Comprehension section.

Selecting the correct passages:

The number of passages asked will be minimum five. If 3 are attempted it is a fair attempt. Passages should be selected based on the following.
1. The Comfort level with the topic of the passage
2. Degree of Difficulty level of the language used
3. Trying Understanding the structure of the passage
4. Knowing Length of the passage and number of the questions asked