Configuring PDZ

Profile Options > Controls

Basics:

Control Style: Standard
Auto Aim Style: On or Off, doesn't make much of a difference, in this game if the small crosshair is over an opponent, the shot is going to hit.
Sensitivity: 75-100 seem to be the best.
Invert Y: Up to you.

The most important part:

X/Y Sensitivity: Off - Most console FPS have Y Slower than X as default, but in PDZ they decided to make it so the X and Y axis are the same speed, it may sound silly, but this makes a HUGE difference when changed.
Y Sensitivity: 45-60 - The Higher your X is, adjust it appropriatly with the Y. This is where you'll be getting more headshots.
Fast Look: OFF - Fast Look is a stupid feature. Basically when you push your analog stick all the way in ANY direction, it will spin you around in less than a second, making precise aiming almost impossible.

Optional:

Options > Game Setup

Camera Bob: Off, Camera Bob is annoying to me, but it won't really affect your aiming too much.

Edit: The autoaim feature actually has a huge impact on ability to aim. When I first got the game I played with it on and off and didnt notice a difference at all, so I played with it off for a few days to feel 1337 but I ended up turning it on. I noticed right away it helps.