I guess it ultimately depends on the look you're going for. An old, dusty/rusty, beat-up clunker of a ship might actually be dull. But most ships tend not to be (especially ones that look sleek and fast like that one), so they need to look shinier.

The trick to shiny is contrast. There needs to be a much greater difference between your lightest and darkest shades. (sometimes to the point where it ruins the "ramp"; there can be a nice gradual shift between the middle shades, but the two on the end need to be exaggerated, especially the light/highlight shade)

Either one is an improvement. I think between those, I prefer the top one, but with the blue "windscreen" area from the bottom.

You could eve take it a little further, and make the dark shades just a little darker and/or the light shades a little lighter. Not by much (too big of a difference can ruin it)

Definitely the one on the right now (at least in my opinion; others may disagree)

The only major issue left is in lighting direction. The shading on the green section implies a light source coming from the left, the shading on the blue implies a light source coming slightly from the right (from the one extra dark pixel on its left edge), while the rest of the ship (the brown) implies a light source directly overhead (because the wings are mirrored from each other in their shading; this is something like the dreaded "pillow shading" you might have seen people warning against)

It is important to select an angle for the light source, then be consistent in applying shading to all pieces of the work based on that (including having raised pieces cast shadows onto other surfaces; for instance, the green section is likely higher than the wings, and should be casting a shadow onto the wing opposite the light source)

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Does that fix the light coming from same direction?

Awesome, its a space invader esq type of game so I figured straight on light would be best.