Shayna Oliveira is one of the experts in the English language. She suggests various techniques to improve pronunciation. One of the most effective ways is the shadowing technique. You have to first hear the native speaker and speak in the exact way how the speaker says the words.
Idhosa Ness founded the Mimic method. It is one of the most effective English pronunciation exercises which you can try. He suggests that you should hear the person whose voice you like. You should then imitate his/her voice. Mimicking will help you in improving the accent and tone in English.