Gustavo,
There are two kinds of sharpening you need (assuming you shot RAW)
1) Capture sharpening. In Lightroom or Photoshop at low to mid ISO, D800 files look best if you sharpen them with a so-called 'deconvolution' (which means mathematically reversing blur) sharpening setting as someone above has said of 60, 0.7, 70, 20 and with all noise reduction turned off altogether. You then tweak this according to the subject, the capture, the lens you used etc... I have this set up as my import preset for all D800 files.
As ISO gets higher you need to make choices about the right balance of noise versus sharpening and this is a matter of taste, capture specifics and subject matter.
2) Output sharpening. This varies according to whether you are going to print the file (and if so, whether onto gloss, matte, pearl paper and what size and therefore output resolution) or whether you intend to use it for example on the web, or whatever.
If you are printing the file I strongly recommend that unless you are using a RIP, the easiest quickest way of getting it right (maybe not perfectly right, but pretty damned good) is to set the print options in Lightroom according to the size and paper type and so on. There are really good tutorials on this at LuLa.
You could spend years learning the dark arts of sharpening. Everyone has their own secret juice, most of which seems to involve long complex routines in Photoshop with curves and layers and masks and modes. Go there if you dare. Otherwise, start as I have suggested above and you will get great results out of the can for most captures.