5. His Appearance Should Be Distinctive, But Not Campy
First impressions are always important, so Mysterio's look should come into play here. Now, Mysterio has one of the most unique looks not just in the Spider Man comics, but in the comic book world as a whole. His most distinguishing feature is as Spider Man refers to it 'that dumb fishbowl on his head'. I am aware Mysterio's look may not work completely on the big screen, and of course if he was adapted as a villain for a movie, it would have to change. However, I think Mysterio still needs to keep some of his signature look in order to keep him intact with the comic book readers. Leave the fishbowl on there you don't necessarily need to make it look like a fishbowl, but in some way it needs to resemble how he looks in the comic book.A way to modernise this could simply be to have something that maybe represents an astronaut's helmet, perhaps like the helmets from Prometheus so he would maintain his 'alien' look, or to have misty smoke emerge from the neck up, similar to the look of the Ultimate Mysterio. This mist can then take the shape of his trademark dome helmet. His trademark purple cape must also be kept there too, however this is a part of his look I wouldn't mind altering slightly as I'm aware it could be seen as rather cheesy. A way to make this work for a movie could simply be a long darker purple cloak, similar to his look in the Spider-Man 2 video game. As for the green bodysuit, that could be kept underneath the cloak it should only be shown slightly and should not be quilted, as that will look extremely ridiculous. A more realistic approach however, would be to dress Mysterio in dark green metallic armor, (possibly built with the help of OsCorp) and a dark purple cloth emerging from it forming a small cape, similar to the Kryptonian's capes over the armor in Man of Steel. The dome helmet could be a helmet that opens up, similar to the Iron Man suit. By tying his works to OsCorp this could also help explain how he has the chemicals built into his suit that help to create his illusions.