Wow, Manupix caught just about everything XD

I guess to reiterate, I'd definitely add more contrast in the values of the lamp and it's shade. It especially needs a sharper texture because it is most likely a smooth, hard surface as opposed to a soft one. That, and it would define it so it can seem more separate from the table. Again like Manipix said, some wood texture/pattern would look nice. Great start though!

Did you draw this from life? I f so, congrats: that's the best kind of practice!

I wouldn't worry about dithering at this point. First, it's not really necessary, also it's advanced (meaning: better none than bad!); finally, it's to be considered only at the last stage (along with AA and other refining), once the main body of work is done (composition, palette, shading). If you do want to practice it because of light gradients, consider texturing. The (supposedly) wooden table would not react the same to grazing light as the wall.

The composition here is a bit boring: centered (both horizontally and vertically) and scattered (no object is big enough to command the view, with lots of useless empty space).

Palette: definitely needs more contrast (in a scene including the light source, blinding brightness as well as deep shadows are expected). Also you presently have separate monochrome ramps: reds, greys, browns etc; you need to unify the palette and recycle the colors throughout the piece (see this interview).

Shading: in a piece like this, light is actually the main subject matter, as well as the material you work with! So you've got to make it really stand out. Integrate the bright spots and shadows in the composition, exaggerate if needed. This is where you've got to really look at the scene in front of you like you've never seen it before: draw things as you see them and not as you know them! Parts of stuff can be lost in highlight or shadow. Inspiration here!