My setup for fine tune:
1. Sturdy tripod for the camera: this is important!
2. Yard stick laying on a table just barely propped up at the "far" end enough that you can see the markings through the camera.
3. A simple cardboard target with a lot of detail on it that is bent to sit upright and is fairly tall so that when it's sitting next to the yard stick on the table it sticks up above the stick and is perfectly perpendicular to the table. Use something like a cutout from a cereal box or something (I like thing like cereal boxes because they are printed with a process that uses millions of tiny dots which provide a lot of contrast to focus on and clearly show when they are out of focus.
4. Set the tripod up with the camera so that it's just above the table and pointing down the length of the yard stick and use the LCD electronic level built into the D600 to make sure the camera is perfectly level.
5. Set the camera to use only one focus point (I recommend using the middle focus point first, as that's the most important one to get right)
6. Put the cardboard target down right next to the yard stick facing the camera (make sure it is well beyond the minimum focusing distance of the lens, move the tripod back if you need to).
7. Look through the camera and put the target under the middle focus point.
8. Set the camera to have an exposure delay (you don't want vibration from you pressing the shutter release to throw off the results). Set custom function d10 to 3 seconds.
9. Put the camera in A (aperture priority) mode - and a low ISO (100 is good) - and the widest aperture your lens can do (that will show any imperfections more strongly)
10. Make sure you have autofocus turned on!
11. Push the shutter button halfway down and let it focus on the target.
12. Push it the rest of the way down and let the exposure timer start then stand back and wait for it
13. Review the photo and zoom into the yard stick right where the target was. The marking on the stick should be most clear right next to the target. A little in front of the target should also be in focus and a bit more behind (Depth of Field (DoF) is 1/3 in front of a target and 2/3s behind it... This is where the old adage comes from to focus 1/3 of the way into a landscape scene for maximum DoF)).
if the most in focus markings are well in "front" of the target (ie closer to the lens) then your system is front-focusing... If it's "behind" the target it's back-focusing.
14. Make adjustments (in AF Fine Tune) and reshoot until you think you have it right.
15. Switch to Live View mode. Use the joystick to put the focusing box on the target. Hold the shutter button halfway and let it focus completely on the target. Snap one off.
16. Compare your best "normally" focused shot against the Live View shot. If you've done your job the photos should be nearly identical.
Live View focusing gives you "perfect" focusing because it's done using e sensor and (as long as it got a good lock on the target) it can't be off. So if your regular focusing matches the Live View focusing you're good to go.
17. If you are using a zoom lens make sure to do this at both ends and in the middle and try to pick an AF Fine tune setting that optimizes all 3. If the lens is wildly different at the different zoom lengths then you'll likely need to send the camera and lens in to Nikon and have them adjust the system. It could be the lens but it might be the camera.
Hope that helps!!!