The key to a memorable rhyme is an extensive vocabulary. Read as much as you can. Reading different genres increases vocabulary and makes it easier to find rhyming words. Scan the dictionary and make notes of some words that appeal to you and that fit your style of rap.
Pick a beat that is unique or even create mixed beats to set the background for the lyrics. Work with a production team in a studio and listen to multiple beats. These beats are tracks before the lyrics are added. Not every beat matches a rhyme scheme, so listen to the beat with and without your lyrics to get an overall effect for the music.
A rap is spoken poetry. Before it is spoken, it is first written. Include your personal experiences in the rap. The listener will feel your emotions in the poetry and become more attached to your message. Speak about your life to make the words more meaningful and thoughtful. Sharing experiences provides the rapper with a creative outlet and helps fans better understand the source of the lyrics.
Learn to use a multi-syllable rhyme pattern. Making more than one syllable in a word rhyme can be challenging, but adds creativity to the rapper's delivery. An example of this is "my cat and hi-hat." The normal rhyme would simply be "cat and hat." Utilizing this skill adds flow to your verses and is worth the extra vocabulary challenge.
Perfect your rhyming skills by performing lyrics for various audiences. This gives the rapper performance experience. Make your first audience family and friends. Ask for and accept constructive criticism for improvement. When you feel ready, perform for larger audiences. Put your skills to test and enter a talent show. Schedule club venues when you feel that you have perfected your rhymes.