Vase

Pros: It seems you have a basic understanding with values and color theory. You created shades and tints with a clear idea of where the light source is. The use of a violet-red color made the vase stick out with it's orange color.

Cons: However, you still have a long way to go. The picture is insanely blurry. The shades of the violet color (I believe it's supposed to be a cloth) make it feel like there is no surface. The way you did the shading, while you understood values, makes it look like it's made out of clay instead of glass. For whatever reason you made the (our left) side cloth extremely dark while the "vase" doesn't have much dark value. Also, the flower in the middle of the vase it just looks weird with it popping out like that. Perhaps it's how you did the shading but there are other places where you left the shading alone and the effect you were trying to go for is ruined.

Suggestions: Firstly, I think it would be wise to ditch that soft brush you're using. I don't know what program you use, but as I see it you're using a fairly soft tipped brush and that just makes it way too blurry. You'll need a hard-tipped brush (or a brush that has a solid streak) for the majority of the picture. I would recommend, when you do your shading, change the opacity of your brush. I would advise that you use the soft brushes to smooth out values if they seem to be too thick. I think using the hard brush tools would not only bring out your vase but also your cloth. Another thing I can suggest for you is to carefully look at light and dark values on vases and cloths. You can simply Google search the items to get a good understanding of how the material effect their values. If you're still having difficulty, why don't you try creating your own still life and work from that? I think that would benefit you more than trying to create something from scratch (I'm just assuming you created this piece from your imagination). One last thing, that left corner doesn't have to be that dark. The vase shows that there is a great light source coming from that direction so, if that black blob is the shadow, it would stretch farther away. By the way give evidence of distance in this piece. It looks so flat the way you didn't provide shading in the background. This is why I mentioned creating your own still-life; so that you have a real-life example to draw from.

Final thoughts: I see by your description that you're learning digital coloring. This is a good start but you still have a long way to go. Don't be discouraged; this stuff isn't easy. Even with traditional materials values can be tricky, especially if one is trying to create a still-life from their imagination. Hopefully you'll find this critique to your benefit and improve. Keep practicing and I am sure you will get better with each piece!