As much as it may sound cliché, you should really get into realism. Every single artist, no matter the style they specialize in, whether it be anime or cartoons or academic style, has to learn and study the basics of anatomy to master their craft. Learn about different poses, the use of shading, the rules of anatomy and perspective, etc. Then, go back to drawing anime. You'll see a huge difference! More on reddit.com

I think that maybe they refer to drawing with reference, since it's kinda hard to draw from imagination. More on reddit.com

The reality of learning art skills is that the best way is going to take time. As much as we'd love a quick fix, the best skills are developed through the time we spend developing them. Once you're able to see your artistic career as an ongoing journey instead of a destination, you're going to have an easier time learning..it may seem counter intuitive but being patient with yourself will help you improve quicker! So with that being said, my advice is to study various poses through life/figure drawing workshops - a lot of poses can be found online. Time yourself, 5, 10, 15 minutes poses. By doing these, it will help you compile a mental library of how proportions are supposed to work as well as how various parts of the body appear in different angles. Cartoons are an exaggeration/abstraction of the human form. To translate this into a manga style, I would study your favorite manga artists and see how they take certain features and exaggerate or modify them to fit their style. The more time you spend solidifying your fundamentals in realistic anatomy, the easier it will be to execute in any style of your choice. More on reddit.com

Drawing cartoon characters is about construction. They are made of simple 3D volumes that you can imagine in your head. Then you draw the details over the top. I don't know if you've thought about it that way but if you haven't there's your problem. With anime style expressions / hands / feet / details there is a language you have to learn. If that's the part giving you trouble it needs more specific advice. You can get by at first by appropriating these elements from other artworks. Hope this helps. More on reddit.com