I'd say trust me you don't want to! but that's not helpful.
I started learning assembly whilst doing my A levels and carried on whilst I was at uni, Assembally is a not so elegant solution that takes many line what you can easily do in C!
still there are uses for it, for example when programming chips, if you run out of memory space on the chip you can use ASM codes to reduce memory size instead of using string C libraries to do things like printC.
honestly there is no easy way to learn,
Assembally is not fantastically intuitive, and certainly will feel like a step backwards when you're used to higher level languages.
Also a lot of what is learned is specific to particualr chips (I learned to program the Motorolla HC11 that's an 8 bit chip, and still takes a while to learn, (it's also now obsolete),
since then I've started programing PIC chips...
a book with structured lessons and tasks is probably the only way to learn in place of real taught lessons.
also you may wish to invstigate some chips and perhaps consider making a programmer so that you can get some actual experiance in programming hardware, and seeig results,
(it's a lot more fun to see real lights flash or motors move than it is to see it simulated on a screen).