So i'm new to the whole photography thing, but one thing that i have immediately noticed is that I need a good system to organise my files...
from my first trip away I've got some 400 NEF files at about 26mb or something each, now when i convert them to DNG (as duplicates) thats another 400x 26mb files
then i save my lightroom files as another DNG and then a PSD and then a JPG so at present i've got 5 files for 1 photo...

obviously i'm not going to keep every photo i take, but what i'm wanting to know is:

a. Do keep both your NEF/RAW files and the DNG duplicates or just the DNG
b. Once you've given it the lightroom treatment do then save another duplicate DNG file?
c. Not all photo's need photoshopping but saving a PSD and then finally a JPG seems to be a step that can't really be avoided...

I'm curious to know what the file/folder structure that pro's use is... would it be something like this:

Date(for NEF) -> DNG (for DNG Files) -> Lightroom -> PSD -> JPG