I have spent my fair share of time living out of bags; in fact for a period of over seven years I didn't spend more than six months in any one place, living on one-way tickets with nothing more than I could stuff into my rucksack and boardbag. I got pretty good at packing.
This past month I've packed bags for two trips that had quite specific constrictions: a bicycle camping trip where everything that I took had to be carried on my bike, and a small boat expedition that necessitated me putting everything into a limited number of dry bags to be strapped down in the boat. I like these sorts of packing puzzles just as much as I like writing lists of what I can pack for a flight that can be carried on my back and on the ends of my two arms without incurring excess baggage fees.
At the end of last year the patagonia cleanest line blog featured a post about packing by one of their climbing ambassadors Brittany Griffith, who uses a "room" system which I really like and isn't too dissimilar to my own technique.
Here's how it works: you probably only need things from three of the rooms in your house (bedroom, bathroom and garage), five maximum (kitchen and office). Each one is it's own bag or sub-bag.
A washbag covers your bathroom packing and really all you need from there is your toothbrush because you can buy toothpaste, soap and deodorant in most places on this planet. My first aid kit is kept in my bathroom, ready to go in there too. Bedroom is clothing so is destination dependant but normally includes a few t-shirts, boardshorts, underwear, and I always pack my finisterre etobicoke insulation layer for cool evenings, air-conditioned airports and to use as a pillow. Garage is for all of the fun stuff like surfboards. Additional "rooms" are the kitchen if you're camping (and need to take a camp stove, mess tins and provisions) and the office if you need to take work stuff.
Surfboards get dewaxed so that the wax doesn't melt all over everything else if my boardbag ends up sitting on the tarmac of a hot-as-hell hub airport during a transfer. If I'm taking a wetsuit then that protects the bottom of my board/s (zip away from the board) and if I'm taking a sleeping bag then one surfboard goes inside that for extra protection. I pack my towel at the nose end and then roll up all of my clothes, secure them individually with rubber bands and pack these around the rails, particularly at the tail end. Fins, fin keys, wax and pocket knife all go in here too.
My "backpack" is a normal (carry-on) size Gravis metro bag, with a laptop pocket (I also chuck a magazine in there so that I don't have to dig around in my bag once in my seat), main pocket and three external smaller ones. The smaller pockets are what's important. Stash passport and boarding documents in one for easy access, and toiletries in the little ziplock bag that they make you go through security with in the other. Nobody wants to be stuck in the queue behind the person who has to dig around and unpack/repack their bag at every stop on their way through departures. I normally stick a bodysurfing handplane in my backpack because if my boardbag goes missing in transit then at least I can still get in the sea whilst I wait for it to catch up with me. I only take a carry-on bag because I'm a pretty firm believer in the "take half as much stuff and a bit more money" rule, although I tend to not take the bit more money because that normally went towards the price of the flight.
All of my work gear is camera kit that gets packed into a pelicase ("have you got any pppelicans in there??!") so that it's safe from water and dust and so that I can carry it onto planes rather than put it at the mercy of baggage handlers because it looks all important, electronic and expensive.
Backpack on back, pelicase in one hand and boardbag in the other (or being dragged along the shiny airport floor). Sorted, and still moveable once beyond the boundaries of the airport trolleys and out into the real world. Oh, and don't forget to pack a good book in there somewhere.