Post-rendering Photoshop techniques?

A simple trick I use almost every time is duplicating the layer, then set it to overlay and playing with the highpass filter.
It really helps with the “pop” and definition of the rendering.
After that just some contrast adjustment and possible adding a few gradients and highlights in necessary.

If you feel like digging a bit deeper into post-PS, Esben Oxholm has some really cool tutorials.

For example this one: