A few months ago I wrote a brief post on the importance of imitation. After that, I actually had been looking for great online materials to improve pronunciation, until I came across this great tool.
This tool allows you to listen to a short audio file and then record yourself saying the exact same thing. And the great thing is that it also has an app that you can install on your smartphone.
When you install it you can start practising right away. Or to save your progress you can register using your email and password which is better in case you like to track your progression.
It is advisable to follow the sets order, but if you think the phrases and words are too easy for you-you can skip the lower levels. Although it is better to practise everything.
And there are quizzes, where you get instant feedback.
Once you are done with this you can move to use more advanced tools like ELSA, the shadowing app, or something like English Paradise where you will find more advanced materials.
And the truth is that you can save your money because you can find any video or audio file that you like and break it into smaller files. And then listen to record yourself saying the exact same thing.
Here is a recommended website where you can find videos and their scripts.