The most elementary QED textbook I have ever seen is "Student Friendly Quantum Field Theory" by Robert Klauber. I don't think it can get easier than that.
A good introductory book, is "Quantum Field Theory for Gifted Amateur" by Stephen Blundell and Tom Lancaster.
I also recommend the excellent book "Introduction to Quantum Effects in Gravity" by Mukhanov and Winitzki. At first one may think this is about QFT in curved spacetime and so isn't proper for someone who's just starting to learn QFT but that's not the case!
IMHO, an ideal combination is:
Lancaster and Blundell --> Schwartz+Mukhanov and Winitzki(with the main focus being Schwartz) --> Hatfield (Quantum Field Theory of Point Particles and Strings)
Of course you don't have to read all the above books cover to cover, but only Schwartz and Hatfield!