We minimize. We choose bottle kits that allow us to carry our products in mini doses:shampoo, shower gel, moisturizer… We do without a hair dryer if our hotel (or holiday home…) provides one.
We roll the clothes. To save space, we roll the least fragile pieces, such as jeans, T.shirts... No, they don't wrinkle! We place the underwear, swimsuits, accessories (belts) in the recesses, or in the interstices created by the rolled clothes. Obviously, it is better to have the most fragile things on top:sweaters, shirts or dresses.
We optimize the shoes. We wedge them in the corners of the suitcase. Before that, we "stuffed" them with socks, tights and other small accessories that we never know where to put.
We limit high-tech. To reduce the clutter of countless power cables (laptop, iPod, telephone, camera, etc.), invest in a universal charger (Fnac, Darty).
We make the trip with the heaviest clothes. We carry on us, for example, the famous jacket which fills half of the suitcase, and which will act as a pillow on the plane. Ditto for the shoes:we leave with our super rangers, which we take for the hike, or with the wedges with super thick soles, which we reserve for the evenings...