If you're on a budget, i'd suggest you start with changing your front brake pads. Bendix Metal Kings are a good value for money pads since they perform better then OEM and cost less then 1K a set. The Nissanbayan peeps use this pads on the track and are quite satisfied with them. This is also what i plan to do with my pickup as soon as i wear out my stockers a little more.
Being a pick-up owner (Frontier), i also noticed my brake problems to be the rears locking up prematurely, especially when the roads are wet. The front rotors are also quite small (they're just as big as my rim center).
Changing to wider, highway terrain tires also helped. Keep you tire pressure in check as well always. Also, make use of engine braking. Since the pick-ups have torquey engines, engine braking helps a lot during those hard stops and emergency situations.
Iv'e been wondering if the Safari brake system (front and rear discs, etc) will fit on a Frontier.
