One of the tools to work on the great packing light challenge is a good and precise scale to actually weigh items. You'll be surprised how much your electric razor weighs and how much a men's shirt weighs - actually about the same at 200-280 gram. That's easily half a pound.
So here is what I use (no connections to the seller at all):
The fantastic MyWeigh 7001DX here
It is a kitchen and postage scale, exact to the gram. It will convert on the fly between grams, kg, lbs and ounces. The LCD is backlit which makes it even easier to read. The numbers stay on even after you take the weighed object off for those times when you weigh something so big it covers the display. It has a tare and a reset option and it is very accurate. It has been to the gram exact with the calibrated scale at the USPS office. It weighs up to 7kg which is not so common for kitchen scales and very handy for luggage purposes. I weighed most of my bags and accessories with it, too.
I have been on the same set of AA batteries for 4+ years but you can use a wallwart. Just bought one for my best friend, too. It comes with a bowl and two postage devices; one for envelopes and one for poster rolls, so they don't roll off.
I use it a lot and it's never given me grief. The seller is also very reliable and the price is right.
A packing strategy of two bags (probably the most common one):
And some considerations on getting a bag with the right volume to weight ratio:
Volume/Weight Ratio as a Luggage Criterion