Practice speaking and listening

Use one of the many online dictionaries which have an audio function, and check that you really do know how words should sound. Most dictionaries have both British and American pronunciation, which is helpful. Many learners think that they know how to pronounce certain words, when in fact they consistently mispronounce them. It is surprising how many advanced learners persist in pronouncing 'word', for example, as if it rhymed with 'lord' when in fact these two words have completely different sounds. They do this because they have never really listened to how the words are said by native speakers. Instead, they rely on how the word is spelt, and how they imagine it ought to be pronounced. Don't make this mistake.

I have the same problem) of course, you need speaking practice, as well as listening one, but as addition to it i would like to advise you a very useful book - "Spoken English. Flourish your language" by Robert Carmen. I've found there many helpful facts about english pronounciation)) good luck)