Good question and the combination of the two is undoubtedly a winning team. However, each of them is already so versatile by itself, that the combination and possibilities of the two are closer to being infinite than in any way limited.
The first question would be, are you focusing the use of Cinema 4D inside of After Effects?
Secondly and not even remotely less critical, is your question perhaps workflow related?
I avoid questions that would require a self-evaluation, except one, to tell me to be a complete beginner, anything else is always too subjective, and not useful - as far as I can tell.
Cineversity has a lot of content for this theme, for example, directly related presentations and tutorials about it, given no further filter to that search.
If you use C4D Lite instead of After Effects, the list will shrink and you will find more material about the use of Cinema 4D inside of AfterEffects. Inside means here, that the Application has a Lite Version implemented in After Effects, which has some advantages, give a specific workflow.
For me, the central part in using After Effects for my productions (as discussed in the JET series here) was [and continue to be] mostly as a compositing application, while using multi-pass more than often. Since everything was in After Effects after the compositing, I often used it as Color Editing Application as well, including finishing.
I have asked the two main question, and they are not the first that I should ask, of course: what content do you would like to produce? Because an answer to this question will lead to different suggestions.
The theme of a workflow can be simple or complicated. The most straightforward answer would be, at which step you like to stop being able to tweak a clip and move on.
One possible pipeline /workflow could be like the one discussed here:
However, this is just one way to do things, and each project might require a different workflow. There is not a lot of limitations here with the Cinema 4D and After Effects combination.
If you would describe your ideas and targets more, e.g., what kind of production you would like to do with these two beautiful applications, then I’m happy to search for material that will support this.
Of course, I’m motivated to look into each specific question. Not that I have all the answers, even using this combination since the mid-‘90s, but developing a pipeline or explore options is always fun.
Think only about the 3D export options from Cinema 4D to After Effects via an ‘aec’ file (after-effects-compositing) or to open a Cinema 4D file directly in AfterEffects, perhaps a combination of both. There is also a way from After Effects to Cinema 4D. This alone offers so much flexibility that individual questions might be more effective than to go through over a hundred videos here alone.
Books about After Effects, my first source, and suggestion would be anything from the Meyers.
After Effects Apprentice: Real-World Skills for the Aspiring Motion Graphics Artist (Apprentice Series)
by Chris Meyer and Trish Meyer
There are others, but I can’t see that they have continued to write. A new book coming in April, but I haven’t seen the content overview.