I'd say the best place to start is to see what other guys have used and how well they like certain kits. Or if they don't like certain kits.
If you don't weld or fabricate the Bolt on crossmember from
http://www.chassisengineeringinc.com/ is as simple as it gets. Measure, drill and bolt on the unit and start installing the suspension pieces. On the other end of the spectrum Scott here on the board can sell you a complete custom front and or rear suspension that will set the truck at the exact height you want it if you give him the right info. another great source but again not inexpensive is Steve at
http://www.industrialchassisinc.com/ who does some incredible work and has repaired and redone who knows how many botched jobs done by other shops.