Listen to as many different rappers as you can and rap along to your favorite songs to get used to speaking in a flow. Dr. Dre, Tupac Shakur, Ice Cube, Jam Master Jay and Eminem are all highly successful rap artists who had all applied their craft over many years.
Write your own rap lyrics.You can rap about any subject that has personal meaning to you and this gives you a form of self-expression that can set you apart from your contemporaries. Keep a pen and notebook on you at all times so you can write down lyrics as they pop into your head.
Attend rap battles if there are any in your area. A rap battle is where you and another rapper freestyle back and forth with the goal being to insult your opponent in the wittiest and most rhythmical way possible. This forces you to think quickly and improvise lyrics while performing under pressure. Write punchlines ahead of time that you can then fit into your freestyles as needed.
Record your best raps so you can assemble a demo that you can then hand out to people and can send to record companies while you attempt to get discovered.
Continue rapping, no matter happens regarding your career. Many rappers have toiled for years in obscurity before landing a big break and that time was used to sharpen their style and perfect their ability. Constant practice is a must if you want to be the best rapper you can be.