Try to bring as little as you can with you - I've now done away with my big back pack, and just carry one piece of carry on luggage. How? By cutting all the "I'll bring that just in case" items out. If the worst comes to the worst, and I need something I've left behind I'll buy it while I'm away.
I use the rolling method - you need a flat surface to do this - a bed is perfect.
first I fold any trousers vertically (so it looks like you've
only got one leg) and I lay them flat on the bed.
next I get my shirts and button them up, lay them flat and fold
the arms inward - as if your arms are crossed over your stomach, and I place them on top
of the trousers (if you've got a small bag then you can fold the shirt in half - fold
along the button line). Ensure that the collars are up with the waist band of the trousers.
next come any tee-shirts, fold the arms in, and again if you've
got a small bag, then fold them in half from top to bottom. Place them on top of the
then comes the underwear - place each bit on top of each other
and put them on top of the tee-shirts, again inline with the collars and waistband.
finally put any socks on top of the underwear.
the tricky bit - grab the bundle at the waistband end and start
rolling, try and make the roll as tight at possible.
Once you've got this roll you can place it in your bag, and if you
can stop it moving around then so much the better. Wedge it with your toilet bag, book,
camera bag etc.