catgut said:
By the way, I have a question out of sheer curiosity.

Have you actually learned to draw using these books?

I'm not really sure how I should practice what they teach. I usually just copy the images but when I try to draw my own characters it's a bit difficult for me.

So, could you give me some advice, please?

The first thing you should be is to learn anatomy is the key to draw characters practice draw their faces depending on the book some are just reference, they teach you to draw by parts, bows, wrinkles types of hairstyle, dresses etc. try to read the book completely just observe what you want to draw, each detail then draw it on your own do not try to imitate the illustrations of the book you should draw with your own style, the book only use it as a guide when you draw for example if you do not know how to draw a line of eye, wrinkle , details of hair skirt etc. consult it with the good book I hope it helps in something just practice and study and you will get to develop your style of drawing / manga / anime