I'd say start chronologically. I have this list with all the movies in the order of which the storyline goes as accurately as possible. I did skip some movies and TV series out of personal preference, and I only began watching the series after I was done with all the currently released movies that were available to me. Everything on this list can be watched via Disney+ excluding the Tom Holland Spider-Man movies which I ended up watching via a private streaming service. I also watched the Andrew Garfield and Tobey Maguire Spider-Man movies via Amazon Prime, I believe, but they are not part of the MCU and I only watched them because I was curious after a certain movie.