You could try singing. Even if you are not a good singer, singing will give you practice in carefully pronouncing words. It is not the same as in speaking, but it will help train your accent.
Watching American television shows might help, but you have to be mindful that some of these shows use slang and improper English on purpose. If you have a good grasp of written English, you might try reading it aloud. This should help because your mind will recognize how the words should sound and be emphasised, so you'll get practice doing it.
Where are you based, hounjorobert? In Britain (my teaching context), variety in speech and particularly in accent is encouraged, as long as meaning is clear. I wouldn't try to change my speech patterns unless it was really interfering with my teaching. Exposing kids to a range of accents, intonation and speech patterns can actually benefit them in the long run. I now teach in an American International School abroad, and the kids make fun of my British accent mercilessly, but I think in a globalised world it is so important for them to be at least used to different ways of speaking. Every teacher also has their own idiosyncrasies, and students use these to identify us - so in short, unless your intonation etc is obstructing communication, I really wouldn't worry too much about it.
Another good source for learning English pronunciation and syllabication is re-run sitcoms like "Friends." While there are some characters with regional dialect (Joey, for instance), overall, the English spoken on such shows is fairly commonplace, and includes idioms and slang that may at first be confusing to non-native speakers. By interacting with popular culture media (tv, movies, etc.), the non-native speaker can gain a better sense of the tapestry of language represented in the United States.
Watch English-language television! Hearing native speakers is one of the best ways to learn a language. A news channel would be especially helpful because you will see the anchorperson as you hear him/her speaking. National news anchors are trained in speaking with little or no regional accent, so their intonation and stress is quite clear and easily understandable by listeners all across the United States.
Good luck in your work to develop your spoken English! I know you'll be successful if you persist.
There are two basic causes of native language influence on accent of speaking a different language.
- Not knowing the correct accent or pronunciation. This difficulty is compounded by the fact that it is difficult for individuals to realize correctly what is their own accent. Also when people learn a language from someone with incorrect accent, they have no opportunity of knowing the right accent. The only solution to this problem is to have some exposure to the correct accent. These days audio and video based teaching aids are available to teach languages with right accent. Listening to Radio and TV programs in the foreign languages is also very useful. If you are happen to have the opportunity to be among people who speak the language with correct accent, that is of course the best source of getting exposure to correct accent. If you can find a friend who can point out your deficiency, it is even better.
- The second problem in getting the right accent is the action of our lips, tongue and other muscles involved in the act of speaking. Different types of accents stretch the muscles to different accents. Thus speaking a foreign language may require you to develop some muscles that do not have opportunity of developing your native language alone. The only way to develop these muscles is by speaking practice. Practice is also essential to make the correct accent a habit rather than a deliberate conscious effort.
What I would recommend you do is practice, practice, practice. I would also get an esl teacher to help you out as you strive to become better at speaking. Speaking is never easy. I had students one time who had difficulty with their r's and t's. If that is the case for you, then it is quite normal. All you can do is keep practicing and working hard at getting better at it. Never give up. I know you can do it.