If you're talking about a 3'er, then you're dealing with struts, not as simple as normal shocks. To replace the struts, you'll need 6 mount nuts- the ones on your shock tower, 3 per side. They're designed for one time use, so don't reuse the existing ones. Then you need 4 strut mounting bolts- 2 per side for the bottom end- some people reuse them with threadlocker, but they're cheap enough that you should use new ones. And you should replace the upper & lower spring pads if your mileage is high. Then you'll need a spring compressor to dissassemble the strut assembly and move your parts over to the new strut. Pay the mechanic $500-$700, look for a DIY, or wait for my DIY in a week or so.
As far as springs go, if you suspect the front ones are weak, now is the time to replace them, since it's a huge pain in the ass to go through the process all over again. The rear springs can wait, since they're easier and not part of the shock assembly. But typically, you want to do all four at the same time to maintain balance, and they're sold as a set of four anyway.
Lastly, if you've been hitting hard stuff like potholes & rr tracks, check your control arms for damage, you'll probably wanna at least replace the control arm bushing.