As Sunlit & Bowtie mentioned...the front brakes do most of the work, start there and upgrade to hydroboost if you want a big upgrade. To do it right (non junkyard parts), you're going to spend $500 - $900....personally, I'm really picky about brakes and only buy new or remanufactured AC Delco for this rig. A simple and much cheaper upgrade is High Performance pads, new brake lines and flush your system.
Rear brakes only handle a % of braking and in IMO, are an awesome visual upgrade, but if you don't upgrade the front first, you're wasting money.
3/4ton calipers on these trucks are WORTHLESS if you don't change anything else, I know, I did it thinking it would help....and I bought new (remanuf) AC Delco's from a '99 HD Suburban application.
Even though the OP is '10, I hope this helps!