The story involving Spider-Man's black costume from the mid-1980s involves a curious timeline--particularly since it plays a large part in the promotion of several existing comics as well as the launch of a brand-new title. We got our first look at the costume when Spider-Man returned with all of Earth's other missing heroes from the Beyonder's planet in May, 1984--yet we didn't see the costume's creation until the eighth issue of the Secret Wars series published the following December. However, Spider-Man decided to abandon wearing the costume in his own title, a month prior to the Secret Wars story where we first saw it, which made its appearance there somewhat anti-climactic.
In the meantime, the costume was given generous exposure in both Amazing Spider-Man and Peter Parker, The Spectacular Spider-Man, presumably to help build anticipation for the upcoming limited series. Once the costume's status as a symbiote was discovered, it would then play a key role in the launch of the new Web of Spider-Man title in April of 1985, where the symbiote would meet its end. From that point, Spider-Man would almost immediately readopt the look of the black costume, switching off between it and his original costume until mid-1988, when Venom would make the scene and snag the black look as his own.
Show me the story conference(s) where that kind of mess is mapped out in detail.
To give you a more sane look at the continuity of the costume/symbiote/whatever, connecting the dots a little more fluidly and a little less promotionally, let's try to get an idea of how a story like this might be approached if we streamline things and tighten everything up a bit. And it seems obvious where to begin:
Yep--this time, at the beginning.