First of all, the entire thing is made up of only and only tissue paper, no glue, no wireframes, nothing else.  
Secondly, the main building block is a rolled up tissue paper tube. Thats it. you use it for "muscles", "bone" and detailing and also to tie muscle to bone and so on.

then there are two ways to make the base body(the lean humanoid you see in the images 1 and 4). You can either directly mold tissue paper into a humanoid or whatever you are trying to make.......it can be best described as fusion of sorts between clay modelling and origami folding (but my method is neither origami, and ofc its not clay but I hope you get the idea) OR you can use the aforementioned paper tubes to make the body. I usually go with option 1 for smaller figs and option 2 for larger ones.

Compression is the key factor in achieving structural rigidity.Use a brush to carefully parts and compress . Compress tissue paper into long paper tubes and then arrange them properly and tie them in the correct places using paper tubes(If you do it correctly you will get something that kinda resembles a "muscle flex")Smooth out the knot using water.

Use water to compress certain parts especially the base structure. It needs to compressed a lot, and once it dries it will become pretty rigid , dont compress the parts you want to be able to move.  
Make sure to "continuous" tubes for the entire length of the torso or for the entire length of the arm or a leg, whatever.Thats pretty much it.

the entire point of me making these figures is to use them as fidget toys and slowly break them down over time and make a new one. These are NOT static sculptures or permanent ones.

I have tried to summarize the whole process, but if you have any questions feel free to ask.  
BTW thanks for the praise !

Huge thank you to everyone on this subreddit for showing some love to my tissue paper art !!!!!!!!!!! A lot of people were asking about the method, so I am going to mention it in the body + There are some of my older creations.