Whenever I move, I always do two declutterings. I sort through my stuff as I pack, and put anything I'm not certain about taking with me in either a trash bag or a goodwill bag. Then at the new place, I do the same while I unpack. You wouldn't believe the amount of things that slip through the first time. Or maybe its just that they don't seem so important in your new living environment.
When moving into a smaller place, I do a third decluttering after unpacking. This is when everything is in its spot and I go through to see if there is anything I can get rid of to make things a little less crowded.
As far as organizing...I have found it's easier if you organize while packing. I generally take a notebook and write each room on the top of one page. Then I try and organize into boxes. This means I sometimes have a couple of boxes going at a time. Then I tape the box up and label it something along the lines of "livingroom #1". Then in my notebook on the livingroom page I write #1 - and list what is in that box. This allows me to unpack at my own pace - if I need something still packed I can see exactly which box it is in, rather than tearing through boxes until I find it.
It sounds complicated, but it isn't really. It may take a tiny bit more time in the beginning but it really cuts down on time and makes organizing the new place easier overall.