Hey Felipe, I like the overall design of the pieces.
For your jet the scale of the plane feels a bit too big in comparison to the pilot's seat which is at human scale. You could size up the wheels and missiles to make it more proportionally balance. For the edges you could make it more sharp and this would make it feel more solid. For example, you could use a hard round brush on the edge of the jet tail (I like to only have transfer on with pen pressure on the controls for Opacity and Flow on Photoshop).
For the subway station you could make your hard surface have a sharp edge instead of smooth so that it could reinforce the metal look that you are going for. You could also give the painting a bit more depth by adding "fog" or atmosphere to the big building structure behind the subway tunnel. That will breakup the midground with the background a bit more, because right now the subway tunnel has a similar value as the building structures in the background.
Replies
For your jet the scale of the plane feels a bit too big in comparison to the pilot's seat which is at human scale. You could size up the wheels and missiles to make it more proportionally balance. For the edges you could make it more sharp and this would make it feel more solid. For example, you could use a hard round brush on the edge of the jet tail (I like to only have transfer on with pen pressure on the controls for Opacity and Flow on Photoshop).
For the subway station you could make your hard surface have a sharp edge instead of smooth so that it could reinforce the metal look that you are going for. You could also give the painting a bit more depth by adding "fog" or atmosphere to the big building structure behind the subway tunnel. That will breakup the midground with the background a bit more, because right now the subway tunnel has a similar value as the building structures in the background.
Hope this helps. :]