Hey there, George! I've seen some of your sketches on instagram, and I have a few tips for you. 
You have a strong sense of form and you have some nice sketches. They are a bit oversimplified though, and that shows through the manga style you choose to draw in. This means you need more anatomical understanding to further push and create forms. A good way to do this is just basic anatomy, read up on muscles and bones and try to think about them when recreating them. We artists don't need all the muscles, but it is good to know which ones moves and makes big and nice shapes.
Secondly, I this also works off the anatomical studies--Work with your shapes and the understanding of shapes. You can get away with a lot of this with anime and manga, but when trying to draw hands or other parts in a 3D world or scene, it shows. Try to imagine everything as big nice shapes and make them fit together!
I also think you are struggling with poses, you can learn about them by doing a bunch of figure drawing and looking at yourself in the mirror when recreating that pose. Remember that male and female anatomy is almost identical, (not shapes and sizes, but the kinds of muscles and bones) meaning that you can simply transfer your pose into your character by understanding anatomy as well!
There are no sketches with proper value so it is difficult to say where you lie there, but I am assuming that you're going to need to work on that, so that you can work with lighting later on. Good thing with studying values, is that you'll have to studies shapes as well--comprehending them will be key in getting good at values.
And lastly, you need to work on your lines. Now, I ain't a clean sketcher. My sketches are rougher than sandpaper. But, that is one big part that makes lineart! Anyway, I hope this was helpful. I'm happy to hear that you've found love for art again, keep us updated on your blog! 
