Some basic tips for sketching or Drawing:
1. First start drawing with pencil instead of pen, marker or paint.
2. Draw roughly whatever you want or like. Like just try to draw a curly hair.
3. Avoid messing or smudging. It will cause your drawing or sketch looking dirty and untidy by rubbing again and again.
4. Give texture in drawing or sketching.
5. Control and Focus on mind and hands.
6. Don’t start by drawing only one line and continue. Use variety of lines so that texture is maintained and there will be less chance of mistake.
7. In the beginning start tracing the drawing or sketch with real or actual image or object. So that you should be aware of difference between the distance and size of lines of actual object and the sketch.
8. Give some shady texture.
9. Start with 2D objects and then practice 3D objects.