Important points to note:

Main point of the paragraph: Read all sentences. Try to understand what is the main point of the paragraph. Find the sentence where the subject of the paragraph - person, event or idea is first introduced. This sentence is likely to be the first sentence or would at least be in the first few sentences.

Try to find verbal connectives: Verbal connectives like but, on the other hand, nevertheless etc provide important clues regarding the paragraph. If you find a negative connective like but, nevertheless etc find the idea being rejected in that statement. The line that states this idea would immediately precede this line. However, a note of caution : Some paragraphs can begin with connectives like However, but etc.

Try to find logical connectives: When a statement lists two reasons, or two concerns or any enumeration of this sort find the the two sentences with the reasons. These sentences should follow the line.

Analogies: If an analogy is given it should precede the real life example. For example if the author states that when a stone is dropped in water, its ripples are felt for some time after the event. If there is a sentence which gives the example of how we are still feeling the ripples of a great event, this line with the real life example must be after the line with the analogy

Definition of subject: Find lines where pronouns like he, it are used. They should immediately follow lines where this noun is defined.