How would you "Pros" out there, recommend getting started with assembly?

So, I have read many great posts here on getting started with hacking. Now, I know this is a life long journey and will take me years to even be decent at it. I started reading books about exploit development and reverse engineering. Each and every book states “I need to know assembly in order to develop my exploits” Thing is, I can’t seem to find any great resources to help me learn assembly. Sure, there are some books out there. But every architecture has a different syntax. With that said, I don’t know if I should learn an assembler like FASM, NASM or AT&T.