1. Pick a topic that you can speak about for three to four minutes. Record yourself giving this speech. Listen to the recording and write down all of the errors that you have heard in your speech. Then, re-record the same speech, and try to correct the mistakes that you made before. Repeat this same speech 3 or 4 times, trying to sound better each time.
2. Watch an American film over and over again, rewinding certain scenes and repeating them out loud.
Be creative. There are so many ways to practice. The main ingredient to success is motivation. If you want to succeed, then you can succeed and you will succeed. If you are motivated to learn, you will automatically start listening to native speakers and trying to sound like them.