Heya Andre,
Well, as Final already said, nice colors as you can see.
The only thing that I can notice here is the text and subtext when you import text you have to think the font that you need to use and what is the best for your case.
Also, I would prefer the render at the center for having the advantage to play with the empty edges of backround with little flow for making it more realistic in my eye + little smaller.
Remember Alt already pressed when you resize + Shift for better quality.
Last, you would darken more your edges for better results in depth. Or some curves or little contrast would be great.
That's all for me
KIU.