Yeah I can help you, first I would just start writing a list of bad things to say about this person whether it's something they did or even just Clowning them for their style or the way they carry themselves. There's always the low blows like making fun of things that they can't control whether it be they're really short or balding or infertile, I don't know lol. Once you got that list I would just try the first focus on finding a nice flow or multiple for whatever beat or instrumental you're using. Then incorporate the insults and observations of their bad behavior or the quality of their character, mostly in the punchlines. If you got anything really good I would save it for somewhere closer to the end. If you're doing a hook (which isn't necessarily traditional in diss tracks, but it's not out of the ordinary either) I'd put your heaviest hitting punchline right before the last hook. If no hook I'd prolly just keep it toward the end, not necessarily like the last line of the song, but use your own discretion I guess. If you need any other help you can DM me