The Use of Articles (a, an, the)

One of my pitfalls in English grammars is misusing of articles. Articles, including a, an, the, sometimes is quite confusing to me. Furthermore, such a pitfall occurs easily especially when I focus on the content of one sentence or the structure of it. Anyway, I am careless, and misusing of articles occurs often. After I studied using of articles through Internet, I found using them correctly is actually challenging.
The articles are divided into two categories. One is definite articles, including “the”. The other is indefinite articles, including “a” and “an”. Literally, when we use “the”, we refer to a specific or particular thing. When we use “a” or “an”, we refer to a general case or thing. For example, I just saw the most popular film in this year, which means I just saw that particular film. In the contrast, I would like to see a film, and here a film refers to any film.
As to the differences between “a” and “an”, “a” begins with an initial constant sound, while “an” begins with an initial vowel sound. An initial vowel sound does not refer to an initial letter of the adjacent word. For example, we use “a European country” instead of “an European country”. In addition we must distinguish count and noncount nouns, and we do not add “a” or “an” before a noncount noun even we want to refer to a general case.
As to the use of “the”, we should note its geographical use. We do not use “the” before names of most countries and territories, names of streets, names of lakes, bays, mountains. However, we should use “the” before names of rivers, seas, oceans, names of desserts, forests, gulfs, peninsulas, geographical areas and points on the globe.
I need to apply the rules listed above to avoid misusing of articles in the later academic writing.