pgraham:

Carpentry is a good start because you can accumulate some skills on the side while you're still making money elsewhere.

Here are a few more related ideas for skilled craftsmanship:

If you want solid money, learn to build good custom sofas/loveseats/ottomans/padded furniture.  There are about a million woodworkers wanting to make gorgeous wooden stuff and only so much demand for it...but there are a lot fewer people willing to make usable everyday furniture, and you'd be surprised how much even the cheapest mass-produced junk costs (go shopping for one sometime), let alone something solidly made...and custom sofas can easily cost over $10K!

Upholstering isn't even that hard once you learn to sew, which isn't too bad either...and if you've got a machine that can do upholstery, you can make and repair all sorts of outdoor equipment.  In my town, the one seamstress with the capabilities to fix and alter outdoor gear (softshells, hardshells, backpacks, etc.) gets more business than she can handle!  So that's another avenue to look at.

Whatever you do, if you get into heavy construction, don't get bamboozled into hanging drywall.  It's the worst job that pays the least.

JS