When reading, pick a single sentence to analyze. Looking at a single sentence will help you understand the way words interact and grammar is formed and help you understand the general principles of sentence structure.
Ensure that you understand the meaning of every word in the sentence. If you don't know what a word means, it will be difficult to differentiate between grammatical components. Use a dictionary to define any words you are unsure about. In addition, keep in mind the basic elements of grammar, and how basic components interact with each other.
Divide your selected sentence into its component parts. Label every element appropriately. Look at the position and interaction of the words. Assign a symbol or abbreviation to each component, and you can even diagram these components on another sheet of paper if it helps you to visualize the grammar. This is known as parsing.
Examine the structure of the sentence. Is it long and winding, with many passive verbs? Or short and forceful, with action verbs? If the writer is skillful, he has chosen sentence structure carefully to help convey his meaning, or to convey mood. Long, digressive sentences, for example, can signify a writer "meditating" on a subject, while short sentences with active verbs indicate the writer is trying to drive the point home with force.
Examine sentence structure to get a better understanding of the language itself, and its rules. Look at the order of the components, and the way prepositions link phrases, the way pronouns are used. By looking at patterns and when they are broken, you can gain further insight into a language. For example, the reversal of a subject and object, or the use of "be" with the past tense, both typically indicate a passive sentence. Look at punctuation and choice of words to learn more about a writer's personal style.