How to properly approach the study and search for the necessary data in the code of an online android application with reverse engineering?

Question

Android

I didn’t do reverse engineering before, because I didn’t need it, but now I’m trying to find the right value received from the server in the Android application code. That is, for example, when connecting to a match, the game sends some information to the server, then loads the received data into a stream, then another stream is launched, at this time the received data is copied to memory, and read from there as int. And in fact, I just can't coordinate it all, what I called is the result of the fact that I rummaged through the running threads, set breakpoints somewhere in the debugger, but all this did not really bring me closer to the goal, because even having found a class with a description of methods for reading characters, numbers from the buffer, which contains what server info, I still don’t know what specific info is there, and whether the methods return exactly what I need. I actually need to find where the application receives a specific string from the server (which changes every time it enters the match), I tried to look for it in the classes for displaying pictures on the screen, but there are a lot of them and I didn’t find anything either. I understand that the approach is not the same, but I don’t know how to approach it correctly, I saw a lot of articles on the reverse of anroid applications on the Internet, but there only: "find the Add.java file, cut everything. Profit, you are a reverse engineer", you can advise how to approach this task, I understand that I didn’t throw off any photos, etc., but it’s unlikely that anyone will look at so much code, plus I don’t really need a solution, I would like something like: “Look somehow from above, look in the main class, or take a closer look at the threads there,