If you're itching to dive into the Illuminati's tangled web, the most approachable doorway for me was the Brian Michael Bendis era: pick up 'New Avengers' from 2005 and start with the early trade collections. Those early volumes set up the team-of-secrets concept — why a handful of the smartest, most powerful heroes started meeting
behind closed doors — and sprinkle in the flashbacks that reveal their formation. Reading that run gives you the personalities (Reed, Tony, Namor, Black Bolt, Doctor Strange, and later members) and the ethical knots they tie themselves into.
After that, I always tell people to go straight into 'Planet Hulk' and then 'World War Hulk' to see the consequences. The Illuminati's decision to exile one of Marvel's most dangerous beings is the single action that ripples outward in the best way: you get the political intrigue in the boardrooms and the absolute, bloody fallout when that plan blows up. It's a perfect example of cause-and-effect across multiple series, and it will make you care about
The Secret meetings you read about in 'New Avengers'.
Once you've done those, branch out to individual members' books to feel each perspective — 'Fantastic Four' and 'Iron Man' for Reed and Tony, 'Doctor Strange' for the mystical side, and Inhuman-related reads for Black Bolt. If you enjoy adaptations, the MCU's variant-take in 'Doctor Strange in the Multiverse of Madness' gives a quick, visual taste of the idea, but the comics are richer and more morally complicated. I love how it forces you to pick a side without easy answers.