@BoomerZ <- Understated comment. It's true, if you want to check anatomy -whole anatomy- porn sites works to find the type of person that you want to model. Of course there is limitations, as you wont find people drinking tea, waiting for the bus, etc. And some of the camera angles might be too exagerated to practice -unless you are searching for just that, but mostly is fine. Use them to complement the traditional sites of pose reference. Also, Pinterest its incredible full of AI nowadays, even for quick references and they don't tell you, while most porn sites say when a picture has AI, so they are even better than normal pages, whoa!
@VibrantFox Yay! So much info! It took me a while to check all of that!
@NickRowler Yes! I still use loomis proportions because they are basic! Of course later I can stylice the drawing, but for general proportions, loomis its a great starting point!
My little advice to add to all this beautiful comments its to, beside pratice, its to have some dolls, action figures, or the digital equivalent, like this ones;



And from the digital front you can of courser use CSP 3d models, Design Doll, JustSketchMe, DAZ Studio -even download some free models and put some bones in them with blender and use them in CSP.
Really, even a 4 image tutorial found with google search engine will work if you understand it, and make your brain click.