It depends. How much do you want to spend and what do you want to do with it?
Mild off-roading and impress the girls? '07-earlier torsion keys and rear blocks, crank the bars a little, and 32x11.50's on 15x8 wheels.
More serious off-roading? Body lift ($250+install), 33x12.50's, and a limited-slip if you don't have one.
More serious? Forget the body lift and get a Superlift lift kit ($1600+install) and a Powertrax No-Slip rear locker (about $350+install).
Desert running since you're in TX? Dixon Brothers long-travel suspension ($4500+install which will be a lot), wider fiberglass front fenders (required) and paint ($1500).
Show truck that won't go off-road? Superlift and body lift both, 35x12.50's on 15x10 wheels ('cause like, if you actually off-road a late-model with 35's you'll snap halfshafts and CV joints pretty quick).