The cyberpunk protagonist of The Matrix makes a good fancy dress source, especially if you want to be a different kind of superhero. White males with dark hair are best able to pull this look off. It is simple, distinct and not too difficult.
Wearing black sunglasses is crucial. Mirrorshades are even more impressive, but simple dark-framed ones suffice. Without them, your Neo will lack his iconic styling.
Slip on a plain black or dark T-shirt with black or dark trousers.
Plain black boots are ideal. Combat boots work well. You may choose to tuck your trousers into your boots, but it does not affect your look.
Find a black leather trench coat. Other fabrics work as well.
Hair needs to be tidy and not obscuring the face.
Start imaginary bullet-time shootouts with your chums—everyone loves it and knows what to do!
Get a buddy to go as another character that best suits them.
Find pictures of Neo or watch the films as this will give you a real sense of his appearance and demeanour. In the first film he has more rugged costume, in the sequels he gets a bit smarter.
Prepare in advance.
If you want to carry weapons as Neo sometimes does, then be sure to know the legality of weapons possession in your area.
Unless you are a Keanu Reeves lookalike, don't go for the Thomas Anderson image, because it will not be recognised.