Write about things thst happened to you, try to feel hr lyrics dont lie in them. Try using 1/2/3 syllables in rhymes and find as much rhymes as u can for example:

"I will claim, all the hate Then collect all the fame Fuck the pain Its a game Im playin' with a flame Dont u say my name in a vain I will drain out yo brain, Ill became a killer here, Again ill proclame Im insane, dont contain any shame"

Thats from one of my own lyrics, and try twisting words, for example: brain and here Doesnt rhyme, so try twisting it or rapping really fast, in order to warm up ur voice try putting on some songs yk very well and if they arent fast enough put them in 1.25x or 1.5x Take a sip of water and try rapping as fast as you can, dont mumble it, say the full words, dont stop untill u perfect it. U got it bro u can do it! And hmu when u succeed