To improve your pronunciation, you need to focus on:
a. the sounds of English;
b. syllable stress.
In this post, we look at the first point.
If you are really, really serious about improving your pronunciation I would urge you to become familiar with the phonemic chart.
It may take a while to master all 44 phonemes. But once you do, you will have a clear understanding of the sounds that make up a word. You will be able to taste words!
Here is an excellent series of videos which are about the phonemic chart.
amalfabian 