Learn to Draw Hatchings and cross-hatchings
Hatching means to draw many parallel lines close together. In difference to normal shading the lines must not touch each other! Although there is still white space between the lines they form to an area seemingly shaded densely.
Cross-hatching goes one step further. When you are doing cross-hatching you to overlay one set of hatching with another set orthogonal to the first one. This way cross hatchings get much denser and stronger than (single) hatchings.
Drawing hatchings requires precision. So practicing hatchings is also a great opportunity to train your drawing precision. First begin to fill empty sheets with hatchings and cross-hatchings without a concrete subject in mind.
When you have acquired some proficiency, you should try first easy subjects. Choose such sceneries that contain plenty of shadow. Try to reproduce this scene without using outlines. Instead rely completely on translating the shadows and dark areas into hatchings. Let the hatchings' direction follow the objects you are depicting. For drawing darker areas and shadows place the lines of your hatching closer together or use cross hatching.
Learn to Draw Shadings
Drawing shadings is more common than hatching. It is more intuitive and requires less experience. When drawing shadings you just fill areas of your drawing by filling it with your pencil. By varying the softness of your pencil, the pressure you apply and the number of shading layers you create you control the tones you produce.
Like when drawing hatchings you can draw shadings by drawing lots of lines. But this time you draw them so close to each other they overlap and blend completely. Shadings created out of lines still have a direction (although not as strong as hatchings). So pay attention to align your shadings' direction with the direction of the objects you are drawing. To make the shading more dense you can apply the same technique as when doing cross hatching.
Another way for drawing shadings requires to draw lots of very small circles close together so they overlap. Shadings created this way are extremely smooth and lack a direction. The advantage: you don't have to pay attention to the shading's direction.
Best you start practicing shadings right now. Take some sheets of paper, outline some simple figures like rectangles and start to fill them with shadings. Try to make them as smooth as possible and use the different techniques explained before.
Again when you have achieved enough practice, try to start the techniques learned on real-world subjects.
Drawing Different Angles and Perspectives
Besides doing shading and hatching the most important skill you need to acquire when beginning to learn drawing, is a profound understanding of perspective.
There are some rules that can help you to construct perspectively correct drawings. But first it is necessary you practice your eye to recognize basic structures.
Choose simple subjects containing mostly straight lines and not too much curves. Then depict these subjects by drawing only the outline. This way you can concentrate on understanding proportions and perspective. But don't stop here, repeat this exercise by drawing the same subject again and again from different angles.
You'll see with each repetition you will understand the subject better and your ability to capture and depict the proportions of any subject will improve greatly.
Your Next Steps in Learning Drawing
These three practices are the most important when learning to draw. There are more basic skills and techniques you could train. You can learn and improve drawing by yourself - just go out and draw life subjects. Start with easy ones and increase the level of difficulty as you make progress.