Writing requires inspiration. Whenever you feel inspired, just write down the lyrics that come to your mind. You need to be ready at all times to write even if it is your lunch break, you are stuck in the traffic or while eating dinner. This way, you will have a lot of music at your disposal at all times. The more you lyrics you share, the more you will be able to sell.
To avoid your lyrics from being copied by others, you need to protect your work by a copyright. It is extremely important because without a copyright, you will never be able to justify claim on your own work. As an alternate to getting a copy right, some people mail their lyrics to themselves in a sealed envelope. That is a possible option but you can not rely on it and should get a copyright if you can.
A demo disc will help in promoting your rap lyrics. If you can not sing rap songs, you can ask someone willing to rap for you. Record a disc and make a few copies to spread as samples.
You can hire an agent to submit your lyrics to a producer, who will then take care of the remaining details. However, it is recommended that you do the submissions on your own, as no one can represent your work in a better way than you.
Social networking websites like facebook, twitter, MySpace etc. are a good way of advertising your rap lyrics. Make your profile on as many social networking websites as possible and post a few samples of recorded lyrics if the website allows.
Try forming social links with people in the rap industry. Sometimes, one social connection with the right person can take you to the heights of fame in literally no time.