A person's speech is directly related to his intellectual abilities, character, temperament and other features of his personality. Hiding his true character or origin, a person can dress according to the latest laws of fashion, surround himself with the most expensive things, but a couple of phrases uttered inappropriately by him can destroy his image in a matter of seconds.
Books, movies, courage, free time
Start reading. Read classical Russian literature, thereby you will increase your vocabulary, erudition and literacy. If you come across words whose meaning you do not know, write them down and look in the dictionary.
Take your time when you speak. Calmly formulate your thought, choose words that will allow you to express the meaning that you want to convey most accurately.
Create a special notebook in which you will write down thoughts that seem witty to you. Reflect on them, imagine situations in which you might use them. And use if such an opportunity is provided.