i think you'd really be able to improve by doing a still life (oh god... those words always make me cringe... i'm sorry i have to use them here) of each of those things by itself. Take your time with each of them and really get all the detail you can out of them, to the point where there's no more outlines--in reality there's no outlines on things, everything's just light, shadows and hues (colors).
the shading is great, you're really emphasizing how you don't need color to see details here, and if you go further and give everything some depth it'll really pop out. Your attention to some of the details really makes the piece, like the lines on the mic and the reflection on the blade, push it further and put in a light source (imagine there's a lightbulb right next to your head, projecting itself down onto what you're drawing. the way it hits the curves, angles and materials you're seeing is how we see depth. You can create the same illusion by putting in a light source on your piece).
everything looks really good, you're on a really good track and in general everything works out really nicely. kiu :)
-panda
