Here's a snap shot of the object I'm drawing:
First, I started by tracing the form of the banana. This way I knew which direction my lines needed to go in when I was drawing or shading.
Approach 1: Light and shadow
I figured out where the light source was and began to draw again, this time with light and shadow in mind.
Approach 2: Weight
The banana seems pretty dense and heaviest where it's touching the table. I emphasized this with dark, thick lines and some details.
I drew the banana one last time. In this drawing, I'm conveying light, shadow, weight and form all at once through line variation.
Lastly, here's all three for comparison: