>>1336039>>1336260Speaking about more practical part of improving your skills.
You will need a pack of A3 sheets, a few pencils with different hardness (usually 2B, HB and 2H), rubber and easel. It will be very nice to find someone who will tell you about your mistakes and generally review your works while you are drawing.
Start simply by drawing straight horizontal and vertical lines, try to use your shoulder to control the pencil instead of hand, then you can try dividing drawn lines in simple ratios, drawing oblique lines with different angles. Don't spend too much time on it, but it's an important exercise.
Then proceed with drawing simple gypsum shapes
>Cube>Cylinder>Cone>Sphere and egg>Prism and pyramidThat's kinda boring, I know, but you need to draw each shape separately at least once. Later you will build all other shapes from these primitives.
Finally, to consolidate knowledge draw some simple compositions made from these shapes.