just think of topics that come up on the top of your head or even find and think of words to rhyme with them, like for example, verbalase beatboxes at his pace, he is the only beatboxer from outer space. so like they don’t have to always rhyme but think about words that sound similar to where you make them rhyme. another thing is practice a lot, do it for a amount of time each day and you’ll get good at it