I am not master to teach others, but I think it doesn’t hurt to share what helped me so far.
This is a crash course in drawing for complete beginners, a summery of points that were instrumental in my progress as a painter and I think should be given priority in your path towards greatness. Each time I learned one of these and started applying them to my drawings I saw a noticeable jump forward in quality.
Step 1. Cubes
This is the first thing I learned in art class back in school. Know how to draw a cube? If you do, you know how to draw everything because everything is just a glorified bunch of cubes.
An art teacher would probably further clarify that everything is either a cube, a cylinder or a sphere, but to me the cube is the most important one. Even a sphere is a cube that ate too many cupcakes, if you think about it. Try combining several cubes to make a car – it’s just a cube on top of a cuboid/parallelepiped.

Step 2. Shading
This has a little bit to do with point 1 on this list. Everything you see around you can see because the light reflects off of it and a major key to the viewer’s eye being able to identify something as a 3D objects, and therefore of making a 2D drawing look 3D, is the difference in brightness between one side of an object and the other. Take a cube from step 1 and then fill one of its sides. Now pick another side and fill it with a lighter shading. Tadaa…volume!

Step 3. Perspective part 1 – Apparent size differences
Things that are further away are drawn smaller than the ones that are closer.

Step 4. Perspective part 2 – vanishing points and perspective lines
Vanishing points are important to make sure that things in your painting relate to one another correctly or your creation will look crappy. This is one the primary causes when something looks “off” in the painting.
In short, make sure you have identified a horizon line and a vanishing point on that horizon line from which perspective lines radiate to the side. Make sure that objects that are pointed the same way follow those radiating lines. Don’t give all the objects in the painting the same vanishing points though. That looks boring and fake.
For a more detailed explanation, find a youtube video on vanishing points – there are a bunch of them.
