Assumed knowledge: Basic Photoshop skills, layers and simple blending.
Concepts covered: Blending renders using filters with blendIf you ever experienced messing up a piece of your work due to a render that didn’t look right then this may be a saving grace for you. By using filters and blending over the render you can get a vairety of different effects.

I’ll run you through an example with one of my favourite techniques. Create a new document with your render and duplicate the layer with the render. Select the top layer of the render and then select Filter>>Blur>>Gaussian Blur and apply the following properites:

Then select the Blending options on that layer and set the type of blend to Overlay and the opacity between 80-100%. This should give you a dreamy effect with brighter colours.

From here on it all you need to do is experiment. I have created the following examples: