@von_Nimmermehr i found this photo from the little mermaid that might help
I also found out in my search that they used refrence video when animating the movie. Pretty cool.
But beyond just getting the anatomy right, if you go back to the begining of the process you might not need to use such an awkward angle.
The begining is concept: what is your idea or story for this piece? Imagine a friend comming up to you excitedly and saying “ hey! Youll never guess what i saw!! Get this, A picture of a mermaid sitting on a rock… looking at something longingly!” You might be tempted to say “okay, what was she looking at? You were so excited, what made it so cool? Was someone over there? Was it a little mermaid type mermaid or a man eating siren? I need to know bro!!! (You say as you shake them)” “ bro thats it thats it!”
So for a picture that is complete you should show the explanation. For most things to some extent, at least so someone can tell someone else what was going on in the picture and share it.
Second is to do a few different (preferably several) thumbnails of your idea to see what is the most interesting way you can how everything that you need to in your story. These can be blobs and really bad scribbles, mine always are, but the important thing is to think about more than one way to do it. Another helpful thing for this stage is to look at what has already been made in the same vein as you—a quick google search for images can give you ideas on what works and how you can make your story different so it is fresh but still familiar.
Then you do work on your composition. When you have a good base of knowledge, reference, a solid interesting idea foundation, and a thumbnail you like you can enlarge it and mess with it, moving things around, trying to make it interesting and clear.
Then you work on your character design and other detail design. You dont have to be in line with the tradition of the genre, you can do something wacky and shape based if you wanna. Characters made out of interesting shapes are interesting.
Then you start to make it look pretty. Rendering and what not.
I realize you probably aren’t doing this drawing for the how to fix your art prompt (december: rock fortress), but this is all stuff they talk about in the how to fix your art live streams. They recently came out with a “ how to fix your art “ course with a book, a checklist, and all the livestream recording pieces that covers this more in depth. It is helpful for everyone, no matter what level they are at. You might like it!
Best of luck with your mermaid!