It's rather good first piece. Maybe try taking it over to the WiP forum and all the kind peers here can lend you a hand. ;)
Thanks for your comment, I can see my mistakes :) This is my first picture in pixel art, in the future I will pay more attention to detail ...
I see you mirrored the red car and turned it blue. I say this because the shadow is on the wrong side of the blue car - so the mirroring and colour changing is easily noticeable.
That aside you have some rather good pixelled scenery and details. The dragon however doesn't fit the scene both compoition wise and technical wise. The dragon itself could use a lot of anatomy work and it's wings are badly pillowshaded. It's body seems oddly smooth, especially considering how textured the surrounded objects are. As is this piece would be much better without the dragon. Especially since no-one has the slightest expresion of fear or reaction to the dragon bursting out from the building.
I see only large red belly. where the dragon? :)