Hey guys! Question about the last chapter of GH3

So, long story short, my dad showed me his guitar hero stuff and I'm literally OBSESSED! He played all these when he was young, and for what he says he was pretty good, buy I'm having lots of issues with the last chapter. Well, actually with the 7th and the 8th one!

So, so far I was nailing all at 5 stars on expert, but Before I Forget and Cult of Personality started to test me; but I made it through, though not with a highscore, but I just can even pass the first hard part on Raining Blood and One's solo. I was wondering if you have any advise, I've tried to practice on the practice room of the game, but even there I'm having lots of issues.