‘Pronunciation‘ is one of the most commonly mispronounced words. This fact should alert you about particularities of English. During its history English language accumulated words of different origins–Germanic, French, Roman and Greek to mention a few. That is why we have to learn both spelling and pronunciation. Because all ‘c’ in Pacific Ocean sounds different, and because ‘Ghoti’ is a creative respelling of the word ‘fish’.
Technologies make pronunciation easier, if not easy. Two could be particularly useful when you prepare a speech:
Recorded pronunciation in dictionaries. Oxford Learner’s Dictionaries offer pronunciation of words in both British English and American English. Merriam-Webster is an alternative for American English. Simply click on a speaker icon and hear how the word sounds. Try to pronounce it. Hear again. Pronounce again. Repetition makes perfect!
Use Google Translate to listen the whole sentence. There is also a ‘Listen’ button in Google Translate, available for both source text and translation. Select appropriate language, click ‘Listen’ button and hear how your sentence sounds. This could be a great training tool for your speech. (By the way, you could even beatbox in Google Translate.)