(If you are new to MCU, then you should start with; Iron Man, The Incredible Hulk,
Iron Man 2, Thor, Captain America and then Agent Carter.)
There is a S.H.I.E.L.D spin-off mini-series, called Slingshot. It takes place right before Agents of S.H.I.E.L.D season 4.
(can be found at ABC's youtube channel).
Marvel Cinematic Universe (#1-4) tie-in comics :
[Last updated: Monday January 8 2018]
Marvel Cinematic Universe
This is the official viewing order for all movies and series in the Marvel Cinematic Universe
Webisodes (Most of them are at YouTube)
Comic Books and Graphic Novels that also follow the timeline: