Trasborg:
I'm totally with Hazel on this one. Again, likely overkill ... but to me, 0.188-wall thickness is the minimum for what a replacement tie rod or drag link should be. Whatever steering box is there, don't forget to beef up the mounts by tying it to the other framerail, and in some cases plating around the frame, too. Jeep frames aren't the thickest things to weld to.
Suspension
Cappa:
A lift kit should do more than simply fit bigger tires under your Jeep. Once modified, your Jeep's suspension should perform better than it did when it was stock. Many lift kits don't. Keep an eye out for quality and completeness. The cheapest lift is not always the best, or worst. Ultimately, for me, what is most important is keeping the Jeep low while still fitting the tires I want. However, I'm more likely to cut and hack body metal or install smaller tires than I had originally planned than slap on some huge, unstable 6-inch lift kit. Quality shocks are also important. I'll spring for monotube shocks to get a better ride, and nowadays you can pretty much get them for any application. I also tend to go for the softest-riding springs I can find. Going cheap on your suspension could result in a rough Jeep that doesn't flex. Think moderation-you don't need the most advanced lift kit available to have a good time. But you don't want to hate driving your Jeep because it bounces like a stone in a blender either.
Hazel:
The suspension is a Catch-22 for me in that I believe in adding a locker before a lift. However, if your locker upgrade involves a gear swap, you'll probably want your newer, larger tires before doing the gears. Just use your own judgment here. In my vehicle, if possible I do the suspension after the gear and axles. With regard to how wild and crazy you go with the suspension, again, I tie it to the axles. If you're running lockers, it's never really made much difference to me if you lift a tire or not. To me, that means keeping things as simple as possible. If your rig was originally leaf-sprung, there's nothing wrong with keeping it leaf-sprung. I like spring-under more than spring-over. However, if you've got a factory coil-sprung rig like a TJ, I really would consider the simplicity and convenience of a coilover conversion. It's usually money well spent if you're into the more hardcore stuff.
Trasborg:
For most of my stuff, I just try to get the biggest tires under it that the stock suspension will allow. That said, on any short Jeep made before '87, I have some kind of issue with the leaf springs, and the harsh ride, or the shackles, or the goofy way the leaf springs mount. If the Jeep is running and driving, I'll start messing around with those parts, usually looking to put in the longest, flattest, widest leaves I can find lying around.
Axles
Cappa:
I'm a gear guy so I usually won't cheap out on my axles. This is the place to spend money because broken axles can stop you in your tracks. And trail repairs on an axle are time consuming and not at all fun. If I can, I opt for U.S.-made parts. You're typically dealing with higher-quality materials and workmanship, which also comes with a higher price tag. Cheap overseas gears and axles with a lifetime warranty will often break more easily than a quality component.
In some cases, I'll try and get by without a gear swap if my motor has the torque to allow it. But if you are increasing tire size more than 15 percent, you should consider a gear change.
For all but the most extreme wheeling, one locker is more than enough when combined with smart driving. It doesn't matter if you choose one of the more expensive selectable lockers or an automatic locker, go with a full case replacement. Lunchbox lockers that fit in stock gear cases and welded differentials are marginal, temporary traction-adders and should never be considered permanent. However, if you are unsure of whether or not a locker is a good idea for you, start out with the less expensive lunchbox locker to get a feel for how it will perform when and if you eventually decide to step into a full locker. And if you only need or have a budget for one locker, always put it in the rearend. A locker only in the front axle is pretty much worthless during climbs thanks to weight transfer. Having said all that, I won't pour a bunch of cash into a crappy axle like a Dana 35 or AMC 20. I'd rather save my pennies and make an axle swap with the gear ratio and locker I want.