I am seeking instruction and re-assurance on my first plumbing project (copper).
This is a fun way to practice and learn on your own. You will spend about $15-20 on materials, and have a bit of practice to show for it.
Go buy eight 45-degree elbows (not street), a five-foot length of pipe, a tee, and a female pipe-thread adapter. All in copper, all 1/2". You will also need a brass female garden hose thread-to-male 1/2" NPT adapter.
Cut eighth short pieces, equal lengths, of the 1/2" copper. Four inches is sufficient. Lay the Tee, roughly centered, next to one of the pieces. The perpendicular leg of the Tee (think of the post of a stop sign) should point away from the copper tube.
Mark the piece of tubing at two points, one at the depth of each of the two parallel hubs of the T. Cut at these two points (this will yield three piece of copper: two are useful, the middle is scrap).
Lay all your pieces out in an octagon. The perpendicular leg of the tee should point out of the octagon. Ultimately, the thing will look somewhat like a garden sprinkler with no holes in it. Dry fit all the tubes to the 45s to make sure everything lines up. If it does, take it all back apart.
One at a time, clean a 45 and the two tubes that go into it. Take your time--good prep work can prevent irritating re-work. Clean the outside of the copper tubing with a wire brush (a 4-in-1 brush has tubing and fitting brushes for 1/2 and 3/4, all on one tool); do likewise for both hubs of the elbow. This is probably the single most important step in sweating copper, and the most frequently overlooked by those new to the process. If the metal is not clean, solder cannot adhere properly.
At this point, you should be working on a flameproof work surface. Out in the driveway, with a ceramic tile underneath, is a decent place to practice.
Apply flux liberally to the inside of the elbow and the ends of the tubing. Insert the tubing into the elbow. Now you get to practice the fun part. Unroll a length of solder from the spool. Hold the spool in one hand, your torch in the other. (I use a Bernzomatic TS8000 MAPP torch. The one-button quick start and auto-off make life much, much easier. They are only about $50.)
You will pull the trigger of the torch and apply heat to the hub of the elbow, moving the torch back and forth to heat the joint evenly. When the flux begins to fizzle and bubble, back off the heat and immediately feed 1/2"-3/4" of the solder into the hot joint. If everything is cleaned and fluxed properly, you will see the joint actually suck the solder in. Repeat for the other hub.
Wipe around both joints with a damp terrycloth towel. Be careful not to burn yourself. After a few seconds have elapsed, wipe both joints dry with a dry terrycloth towel, being sure to remove any surplus flux from the tubing.
Repeat this process all the way around the octagon. Work slowly, getting a feel for the proper amount of heat (too much will discolor the copper-ugly-and boil the flux away-bad). The T will be soldered in place between the two short stubs of tubing.
Cut another short piece to go between the T and the female threaded adapter. Likewise, clean and flux it and solder it into place.
Once all of the joints are finished, you should be left with a female 1/2" NPT adapter feeding into a closed loop. Once it has cooled comes the fun part.
Wrap the 1/2" NPT male end of the brass adapter in two full spiral counterclockwise wraps of pipe tape. Thread it into the female port at the base of your octagon. Put a washer in the female hose-fitting end, and screw the contraption onto your garden hose.
Turn on the water. If you have done everything properly (particularly cleaning the pipe ends and fitting hubs), you should be leak free. If not, you get to try again.
If you can build one of these things successfully, you know how the basic mechanical skill of soldering copper. Better to play in your driveway for an hour or two first and have your neighbors wonder what the hell you're doing, than to dig into a project indoors and run into trouble.
The biggest difficulty you're going to run into indoors, other than working in close spaces next to flammable things (necessitating a heat shield, a bucket of just-in-case water, and some basic caution), is water in the pipes. One drop of water at a joint will keep it from getting hot enough to melt solder--you could apply heat from a MAPP torch for 3 hours and never be able to solder it.
You will need to drain your house well, and engage in some creativity if drips emerge. I like the little gelatin ball plugs; others prefer bread (aye!); still others prefer the jetswet and similar devices, where they can be used. An air compressor with a blowgun can also come in handy. Be careful with using a shop-vac to suck the water out of piping; I have seen these create a deep enough vacuum that they draw water out of the water heater.
Good luck. Clean the joints thoroughly, flux them liberally, and practice a lot before working on anything important. Sweating copper is fun, and truly an art form.