Sadly, despite having read about them about a dozen times, I still don't understand how they work, or rather how to use them. Apparently, that's because of insufficient knowledge of the relevant part of physics.
https://www.amazon.co.uk/QED-Strange-Theory-Penguin-Science/...
I mean, they are, but only after you've learnt about the machinery behind them. For instance I wouldn't know how to convey the difference between fermionic lines and the bosonic ones without working through commutation and anticommutation relations, the gamma matrices, spinors, the different propagators and so on. Saying simply that fermions are straight lines with oriented arrows, bosons are wiggly lines and we'll draw them like this... doesn't help much when it comes to understanding what they mean, in my opinion.
https://www.amazon.com/Renormalization-Methods-William-David...
two good (Gentle) senior undergrad books are
https://www.amazon.com/Student-Friendly-Quantum-Field-Theory...
https://www.amazon.com/Field-Quantization-Walter-Greiner/dp/...
and then there's always griffiths
https://www.amazon.com/Introduction-Elementary-Particles-Dav...
note that you don't need to read this cover to cover if you're not interested in actually doing calculations. you can skim.
This guy (Dietterich Labs), does in depth (steps) derivations of cool QFT stuff. This is slightly unique as they are less handwavey than lectures (Which are often supporting written material, or at least harder to follow online) and also more informative than the calculations in some books (I think Peskin and Schroeder can be horrific unless you have someone to ask stupid questions too, if you're like me [Well read, but not that sharp on the bell curve of academic bragging rights])
Quantum Field Theory for the gifted amateur is also pretty great (And Pretty actually), Zee for the working man or something like that