Thinking about a full suit, I would begin by combining crumple-zone capability in the outer skin, with just-in-time impact cushioning in the inner skin.
I'm sure we are all familiar with this kind of toy:
When squished, the soft bits "ooze" out of the netting.
Now, consider this toy as a metaphor for the construction of our exo.
First, the exterior (and overlapping) plates would be extremely rigid, such that impacts are spread across a wider area. These would be Mandalorian armour style plates, but many more of them. They would not be smooth, but rather knobbly, with plenty of curves, to aid in deflection of projectiles.
Behind the plates would be a strong but flexible continuous interlocking mesh, perhaps something like this:
Not in discrete pieces, like the picture, but rather continuous across the entire suit. Flexible enough to permit movement of limbs, but strong enough to retain its shape during compression. Notably, the mesh is thicker and stronger towards the outside, getting thinner and more flexible the closer to the skin we get (or perhaps the other way around - a few crash-tests will help determine which). I envisage a 3D-printed mesh for this purpose: not only would it then be possible to make the suit exactly fit the wearer, but this also allows the interlocking, which would not be possible to build with conventional manufacturing.
The mesh layer has membrane coatings on both the inside and outside. A bit like a wetsuit, only considerably more resistant to rupture than neoprene, with the outer membrane much stronger than the inner one. The interlocking mesh is bonded to the membrane (both inner and outer). It is important to note that the inner membrane must be a smooth fit against the skin, across the entire body. There must be no gaps. This should not be difficult since the suit will be a perfect fit for the wearer.
In between the membranes, is the "squishy" layer. This is a thick viscous fluid that surrounds the mesh and occupies all the space between the inner and outer membranes.
How It Works
When there's an impact, the armour-plating serves to distribute it over a wider area, thus diminishing the actual PSI of force acting on the body.
But as the armour plate moves against the outer membrane, the mesh bends and flexes with the impact, spreading the force out even further (due to its interlocking nature) and transferring it into the fluid.
The fluid (which is incompressible) perturbs the inner membrane only slightly, and over an even wider area in turn, ensuring that the actual impact that reaches the body is a small fraction of the force it began with. To illustrate, a "Superman punch" in the chest might be felt as increased pressure across the whole front of the torso... but would not be enough to do any significant internal damage.
The mesh could be made up of nano-poles that generate tiny amounts of electricity when the poles are compressed. And the fluid could be electrically responsive, turning thicker in the areas where current is applied. The result is that the fluid thickens automatically and instantly in the areas where the poles are compressed due to impact.