The best mod overall is a 3" lift. 4" or more may even be better. Most guys who have a 4 1/2" to 6 " lift started with a 3". Some club members may have 3" springs and shocks in the garage that they could offer to you at a discount.
Several club members got together to provide me with a 3" lift for my truck after I repaired it from a rollover, and it makes all the difference in it. Even with stock tires, it makes a distinct difference in handling. I am still stuck with the stock tires, but the lift makes them tolerable.
I not only have more clearance off-road, but the truck handles better on the highway on curvy roads. I wheel it rather gently with the wimpy tires, but without the lift I probably wouldn't take it out at all, at least not until I get some real shoes for it. The lift is it, and I thank all of the guys who came up with the parts for it.
I have installed a winch that I use to remove fence posts around the house, a front bumper that has subdued a Taurus, some creature comforts inside such as DVD players and storage. But of all of them, the lift has been the only thing that I would pay for twice! And I didn't even have to pay for it the first time! Thanks, Guys!!