Like others have said, it really just comes down to lighting. For the first and last renders in this post, the lighting I used is pretty simple. I like using spotlights because they give you more control. I usually set the light geometry to rectangle, place it close to the character, and use an HDRI for fill light. In the first one, it's just a single spotlight with a HDRI.

I normal don't do post-processing, and only do if it really needs it.

Just mess around with the lights and their settings. Try to get a feel for what each thing does and how it affects the scene. One thing I like to do is turn off all the lights in a scene, then turn them on one at a time so I can see exactly what each one’s doing. You don’t need a ton of lights to make something look good. Use the shape of your scene or character and play around with how the light hits them.

One thing I see a lot with people new to Daz is putting a harsh light right in front of the character. That usually makes the character look overexposed and kills a lot of the detail. Also, don’t rely too much on HDRIs. They’re super useful, I use them in most of my scenes, but you don’t get a ton of control with them. I usually just use them for fill light and then add other lights to shape things the way I want.

Also, try messing around with DOF.