IMPROVING YOUR PRONUNCIATION
'Mimicking' means copying everything about the way the speaker speaks, as exactly as you can, not just repeating the basic word pronunciation. "Everything" means, a) the pronunciation of the words, b) the way several words are (sometimes) spoken as several linked sounds, almost like one long word, and c) the way the speaker puts greater stress on one or more words in a sentence.
Similarly, mimicking the recordings in excellent British English books such as "Headway" will help you improve a lot.
Alternatively, you could choose to mimic recordings of American English if you want to. But too much "mixed" pronunciation (a mixture of British and American pronunciation) might, at times, confuse a listener (the examiner).
Overall, mimic imported recordings of native speakers, not domestically produced materials, which are inferior because the native speakers in those materials are not professional actors and often do not speak 100% naturally, especially at natural speed, with naturally linked sounds.
Although "Side by Side" is one of the best books you can use to improve your spoken grammar, the recordings that go with those books are not the best for improving your pronunciation. The "Side by Side" recordings are quite good for helping you with some aspects of your pronunciation, especially sentence stress and rhythm, but the recordings are sometimes spoken at an unnaturally slow speed, especially the recording for Book 1. This is understandable since the main purpose of "Side by Side" is to help you learn to make grammatically correct sentences when speaking.