Learners of English as a second language are usually worried about their pronunciation and feel self-conscious about their accent. While you tread the rocky road of learning to discriminate sounds that are not relevant in their own language and, therefore, are virtually unheard by your Spanish/French/Italian/Portuguese/etc. ear, here is some good news for you: it is OK to have an accent – even a heavy accent – as long as you are understandable.
Does this mean that you don’t need to learn the difference between the sounds of “ship” and “sheep”? Alas, the answer is no. You need to learn to discriminate and produce more vowel sounds than those you are equipped with if you are Spanish, French, Italian, Greek, Turkish or Chinese (I’m sure this applies to other languages, but I’m afraid I can’t quote my own experience there).
What’s the good news then? The trick is intonation. By tackling the intonation issue you will have solved at least half of your communication problem. The difficulty here is overcoming self-consciousness. Once you shake off that useless reluctance to sound clownish you will really be way more understandable. And your communications skills will sky-rocket.
Try it! Start singing the music of the English language.