What do I need to see before Spider-Man: Far From Home?

It concluded the Infinity Saga and starts where Avengers: Endgame left. From comicbook.com

"Those were the films that were culminating the entire Infinity Saga of the MCU. And as we were working on Endgame we realized that the true end of the entire Infinity Saga, the final film of Phase 3, had to be Spider-Man: Far From Home, because

spoiler

we lose Tony Stark

at the end of Endgame.

"The relationship between Peter Parker and Tony Stark is so special over the five films that Tom Holland has portrayed Spider-Man in the MCU, that we needed to see where his journey went, and see how does Spider-Man step out of the shadow of his mentor, Tony Stark, and become the true hero that he was always meant to be. And it's for that reason that Endgame and Spider-Man: Far From Home are essentially two pieces of the same story, and it's not over yet until Spider-Man: Far From Home."

And of course, you need to see Spider-Man: Homecoming (which you already saw) where Tony and Peter escalate their relationship which started in Captain America: Civil War.

And to understand Avengers: Endgame you need to watch Avengers: Infinity War and for that, you need to watch a lot of films. For this, refer to this question:

What films to watch before Avengers: Infinity War for better understanding?

Also, you can refer:

Do I need to watch Ant-Man and the Wasp and Captain Marvel before watching Avengers: Endgame?

Having just watched it I can say that you don't really need to have seen a lot of the MCU to understand what is going on in Far From Home. Of course you should watch Homecoming as you already have done as that sets up the characters for Spider-Man.

The film also deals with the fallout of Endgame as quite a major point. Therefore, to understand it you really need to watch Endgame and to understand Endgame you at least need to watch Infinity War.

You might also consider watching Civil War as that introduces the Peter/Tony relationship which is quite important for the events of Far From Home.

I also have an answer over on SFF where I discuss what one should watch before watching Endgame. However, if you're not too much of a fan of the rest of the MCU and only really want to watch the Spider-Man side of things I'd suggest just those 4 films are the core to get to grips with the story of Far From Home.

Far From Home does make a few references to the early Iron Man films which are quite nice and so would enhance your viewing but they're not really necessary. The most important ones are shown in flashbacks and the little details are more to do with how Peter is like Tony which are more subtle nods and clues.

I'd say you might want to at least watch Iron Man here as Far From Home does deal with

the death of Tony in Endgame

and understanding why that is so important at least starts in Iron Man. You'd also then pick up on more of the subtle nods I mentioned earlier.

The other two answers are correct in some way, but I would suggest watching all MCU movies before Spider-man: Far From Home. MCU is an inseparable story of all superheroes, and trying to pull out a whole story of one them is not really good, because you still won't understand some parts.

If you really want to go to the cinema now, then I suggest watching at least one of Iron Man movies, Captain America: Civil War, Spider-man: Homecoming(that you have already watched), Avengers: Infinity War, and Avengers: Endgame if you can find it on the Internet(I personally have found a 720p version, and it's quite good). Watching these films will help you understand part of Spider-man story.

If you don't have to go to the cinema now, then you should watch all MCU movies in chronological order(here is the order), and wait for Spider-man: Far From Home go online.

Good luck in becoming a Marvel fan!