I have no idea which movie is which any more.
They all blur together.
Which ones are grouped together with related story lines?
I can understand because they made so many in 10 years. But once you watch them all. They start making sense again.
Good question, they all have a good storyline in them and in post #2 is the proper storyline order to watch. But there are some you can skip which can take you to Infinity War.
Iron Man - Begins the storyline
Thor - Introduce Loki
Captain America: The First Avenger - Infinity Stone "Tesseract" (Space Stone)
Marvel's The Avengers - Avengers vs. Loki
Thor: The Dark World - Infinity Stone "Aether" (Reality Stone)
Captain America: The Winter Soldier - When S.H.E.I.L.D. no longer around, but could possibly be skipped?
Guardians of the Galaxy - Infinity Stone "Orb" (Power Stone) and Thanos kids
Avengers: Age of Ultron - Infinity Stone "Vision" (Mind Stone)
Captain America: Civil War - Avengers team splits up and fight each other
Doctor Strange - Infinity Stone (Time Stone)
Thor: Ragnarok - Thor vs Hulk and has Thor sister which possibly leads to Infinity War
Black Panther - Introduce the world to Wakanda
Avengers: Infinity War - Brings together all 18 movies of 10 years in the making
Soul Stone - hasn't been shown yet, but there some rumors that Wakanda is the (Soul Stone)
Also, Guardians 2 post credit introduce Adam Warlock but won't see until Avengers 4 or Guardians 3.
Partially spoiler alert but this is the real storyline from the comics like 30 years ago of what I recall. Adam Warlock and Silver Surfer defeat Thanos as Gamora now controls the Infinity Stones.
But since Disney Marvel doesn't have the rights to the Silver Surfer. They will have to re-right the storyline from the comics and defeat Thanos somehow.