Adding in paintings on photoshop

To test out different ideas for which colours work best in the space, I have begun editing the paintings in to the space on photoshop. This has been a good way to try out combinations of colours and shapes, however I don't really like how it looks as they clearly are edited in and I don't have the photoshop skills to improve this. I found that because the space is dramatically lit it doesn't translate into photoshop, especially in the images where the light is cast over the paintings. I want to use these as a way of deciding which paintings to permanently put in the space and take pictures of so that the colours and the light can mix together in a way that doesn't look artificial.