When drawing with pencil you need to be able to create a wide range of textures for surface effects.
Here are some examples created with a 2b pencil.  By varying both the pressure and direction of your strokes you can achieve a texture to suit your needs.
1. Jagged vertical strokes
2. Short, loose, vertical strokes
3. Long, loose, vertical strokes
4. Short, loose, hatching strokes (diagonal strokes)
5. Long, loose, hatching strokes
6. Standard soft hatching and cross-hatching
7. Loose, 'squiggly' lines
8. Dots

Next time I'll do a sample drawing incorporating all of the above.  In the meantime practise these and it will help to improve your pencil control. All the best, Phelim.