I’ve got a series of omnibuses that put them into release order, and you know what, it’s actually hard to follow a little bit if you only read it in chronological order, never following a single set of heroes for more than a few issues at a time, at least for me.
What I do instead is, I read a few issues of a title at a time, leave the characters in a good place, and then switch to another of the four titles for a few issues, rinse and repeat.
The titles rarely cross over, but they are linked, so I think it’s somewhat important to keep the others in mind. For example, a young Mister Miracle might have a backup story in New Gods. Therefore, I think it’s important to know each set of characters, and not read all the way through every series individually.
Some things to keep in mind:
First, Forever People # 1 has Jimmy and Superman in it, but Jimmy has a different design from his own title, and it’s Darkseid’s first full appearance, so even though it came out after a few issues of Superman’s Pal Jimmy Olsen, I’d say it feels like it comes first, and I’d read that before anything else for that reason - and also because it does a really good job introducing the magic of Kirby’s worlds.
Olsen # 147 pays off Superman’s story from Forever People # 1, even though that’s way later, and almost the end of the Kirby Olsen run. That has nothing to say about read order, I just think it’s worth keeping a connection between those two issues in mind for Kal’s arc.
Secondly, you don’t get “The Pact,” which is perhaps the most important of the whole saga, until New Gods # 7. Even Kirby said that might have been a little too long to put that story off. You may or may not want to skip ahead to it and back again, your call. I think linearity has merits too, one of which is simplicity.
Third and most important, some of the series end kind of weirdly. Forever People is pretty straightforward, it ends on issue # 11. Kirby’s Jimmy Olsen run ends on issue # 148, also pretty straightforward. New Gods ends on issue # 11 as well, and all three of those ended in 1972. Mister Miracle was the last “Fourth World” series to be cancelled, and it ran 'til issue # 18 - which has a lot of characters show up from New Gods and Forever People, so I think maybe read that one last of the original bunch.
However, the New Gods and Mister Miracle series numbering were both resurrected like Frankenstein’s monster in '77 for different writers to do a worse job than Kirby. Ignore all New Gods issues after # 11, and all Mister Miracle after # 18, for that reason.
New Gods did however, come back as a reprint series in 1984, of six issues, each reprinting two issues of the original series. So the first issue reprints New Gods # 1 and # 2, & so on. The only really important issue of the '84 New Gods series is issue # 6. This is because the second half of that issue is new content, following up New Gods # 11, and leading into “The Hunger Dogs” graphic novel that is, I think, Kirby’s last major work on the franchise.
I think you may well choose to ignore that last half-issue and “The Hunger Dogs”. For one thing, Kirby was in a vastly different place when he wrote 'em, and in some ways they’re pretty different, thematically. I’ve also heard DC kind of butchered them in terms of moving scenes around and such. That said, there’s also some really beautiful pieces of Hunger Dogs, here and there. Your call.
Sorry if that’s not too concrete of a reading order! I just think these are series you can go back to again and again, not always reading them in the same order, and that’s kind of great!