There is no magic in a bicycle braking system. The variables are caliper leverage, handle leverage, pad-to-rim coefficient of friction, mechanical losses such as cable-to-housing friction or pivot drag, pad toe-in, cable housing compression, slop in the caliper pivots, and flex in the caliper arms. The others have already provided excellent advice on brake pads and cable housing, as well as stepping up to a higher-quality caliper (Weinmann Vainqueur 999 in either 610 or 750 length, or the DiaCompe equivalent). If you want to boost your braking force by another 10 to 15 percent and can accommodate the 10 to 15 percent longer lever travel that comes with the territory (No Free Lunch), switch to aero brake handles. My Bianchi has the often-excoriated early-generation Campag. sidepulls, which provided unsafely lousy braking when equipped with non-aero levers and Shimano pads. Changing to Shimano aero levers (sorry, Italian purists, but they fit my hands) and KoolStop salmon pads made a huge difference in safety.
__________________
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069