Personally I’m sure that if e621 had some kind of ‘following’ functionality I would probably follow hundreds of artists but as far as I know e621 doesn’t provide this kind of functionality, so how I usually keep up with my favorite artists’ posts it’s just manually searching by their name but just as I said, I easily know more than a hundred artists and usually going one by one is pretty tiring, besides, how am I supposed to know the name of each artist? I barely know by heart the name of the ones I usually look for, but there are many others that I just favorite a post I like and forget about them, because I forget their name and I have many favorites…
I’d just set up multiple bookmarks with groups of artists in each one, grouped by style or usual content.
There’s a ‘search help’ link next to the search bar that has info on all of the weird tags you can use; it links to this guide.