We need a little more info about the truck, and what you want out of it. You have some options, but they depend on the type of suspension.
For 2wd coil spring trucks, you can buy 2/3 (drop springs, flip kit, and lift shackles) or 4/5 (drop springs, control arms, flip kit) drop kits from DJM, or 3/5 (Drop coils and leafs) from Belltech.
For trucks with Torsion bar suspensions, you can crank the bars down, or flip them for up to 5 inches of drop, and the rear drop options are the same as the other trucks.
If you have coil springs, you can also do a quick, cheap drop by cutting your coils (don't go more than 2 inches, or it won't be alignable), and flipping your rear shackles for a 2 inch drop in the rear.
The best advise is to look around through the street truck of the month gallery here, and pick out the look that you want, and copy it.