On this video, portrait photographer Nathaniel Dodson (from the website tutvid), looks at adding a gradient map to your image.
So a gradient map will make the darkest part of your image colored by the color that you choose on the left side of the bar while the brighter colors will use the right side of the bar – pretty simple actually. Now you can basically go wild and create a new layer by going to layer>new adjustment layer>gradient map.
Now you can play with the exact colors, you can even duplicate this layer to get an extra boost but you will likely get an image with too much contrast. To fight this begin by adding a brightness/contrast adjustment layer and reduce contrast to about negative 40/50 and when you will later add the gradient map your image will not be too “contrasty”.
In the past photographer Jimmy McIntyre demonstrated how to combine 3 exposure blending methods in Photoshop to create a natural looking HDR image using a gradient mask which you can check on this video – here.