Question: Im trying to create some realistic mockups of canvas prints laying next to cars, or even hanging on walls. Need to know that extra step i need to know to make these look real. [![enter image description here](https://i.stack.imgur.com/EuHYj.jpg)](https://i.stack.imgur.com/EuHYj.jpg)

Answer: 
1) When combining images from multiple sources, ideally you want to use images of the same quality. The color looks fine but the quality of the canvas/text looks much nicer than the background. I would suggest finding a higher-resolution background image. You can also tell by the sharp border of the canvas.

2) Adding subtle shadows. Add some slight shadows to the right of the canvas.

3) The canvas perspective looks off. The left side shouldn't be much smaller than the right if we are viewing a front facing. I am basing this on the bottom of the canvas which isn't turned much.

4) Make the sign sit closer to the car. It looks like the sign needs to lean onto the car to stand up but in the photo it looks like it isn't leaning back. I would just raise the whole canvas thing up above that circle thing.
This answer is rewritten. I also edited a little your image to make it more consistent.

All this is only based on my speculations because there's no facts available about the wanted forms, positions and colors.

[![enter image description here](https://i.stack.imgur.com/3ephO.jpg)](https://i.stack.imgur.com/3ephO.jpg)

The edits:

1. The text plate is straightened. I wanted to drag its bottom end towards the bottom left corner to make it more tilted against the car, but I hadn't the original plain image. The tilting reveals more of it.
It probably would be a good idea to mirror the original photo left-right. Then the text could be in the light and still stay at the left side of the image and lean against the car skewed as you originally wanted it.
2. I reshaped the visible narrow side of the text plate to approximate projected rectangle. The white stroke at the right vertical edge of the plate was removed
3. The narrow side was made brighter to stay in accordance with the light direction in the original image. A shadow is added respectively at the bottom.
4. A small reflection is painted to chrome
5. The plate is blurred approximately to the same unsharpness as the original
6. The image has got a little contrast because the blurring made 365 CHANCES difficult to read. 1 YEAR= was too bright, so it was kept out of the boosting
. It still is a little too bright.
7. The plate and the original image had different colors. I desaturated all and recolored all to the same hue and saturation. The hue is random. As well it would have been possible to leave it fully desaturated or to copy the hue from your image.

The photo is so unsharp that there's no need to worry about canvas texture and how it is taken into the account in the appearances of the texts. This becomes a problem in higher resolution images which show the canvas details.