Hi Efeifere Barbosa, I'm a teacher both here on iTalki and with International House. There is no easy fast-track way to improving your English. Just as with all of the other skills, writing, reading, and listening, the only way to improve is by doing it! You improve your speaking by exercising the skill and by building it into your every day life. There are, of course, many different things that you can do (build your vocabulary, your knowledge of grammar structures, etc.) but if you're not using the language on a weekly or daily basis, you won't see much of a improvement in your fluency!
SPEAK. SPEAK ALOT. MAKE MISTAKES. LEARN FROM THEM. SPEAK SOME MORE!