When you practice this tip, you won't be able to speak English like a native speaker forever, but it will give you a small idea about the American Accent.
Follow these steps in order to realize it:
1-Find a short sentence being spoken by a native speaker (MP3 file if you can)
2-Listen to the MP3 file many times.
3-Try to speak exactly like the native speaker.
4-Practice it many times up to the point you speak like the native speaker.
Well, what do you think about your pronunciation now? is it good to have an American accent?
Tip: If you couldn't realize it, it's because you didn't focus on the intonation.
Focus on the intonation, don't focus on each single word!