Leonardo Giordani has published since late May a 3-part series with an overview of the Amiga machine language programming.
Giordani objective while writing the article was, in his own words, not intended to be a complete tutorial about Amiga ML programming, but a collection of his notes while exploring the machine architecture. Don’t let this statement dissuade you, because the articles are fascinating and give an excellent overview of some aspects of assembler programming for the Motorola 68000.
It is not an easy topic for us, mere mortals, but Leonardo did a good job making the subject a bit more accessible. The first article also explains how to set up a simple cross-development on a Linux machine, which is a nice bonus!