A number of the recommendations above are good, but I think it is worth mentioning that, when you start watching the foreign movies, don't be discouraged if you can't make any sense of what is said. Consistency is the key, brother.
I think you should also avoid Korean movies subtitled in English; a number of the subtitles aren't accurate. So stay with American and British movies.

Do search for Tofadefama on IG as he helps Nigerians learn how to pronounce words in the ��British way so as to sound British��.

Language is a large system. You may have difficulty speaking because you are afraid of making a mistake or you are embarrassed about pronunciation, or perhaps you simply lack vocabulary or knowledge of grammar, and therefore it is difficult to formulate an idea. Now I’m actively studying with english grammar tutor, but I won’t say for sure that we only study grammar. Rather, it is still the same English, just with a greater emphasis on grammar.