Easiest way I know if to find a small time outfit and become a helper. There's no substitute for on the job training my friend, just make sure to not try and pick up bad work habits.
Just go into a hardware store and ask for a 1/2 boiler drain. Which can be be sweat or thread (male). You'll have to try and melt the solder off the old valve and re-sweat (solder) the new one on. Be mindful that you can't have any water in the pipes or the solder won't take. If you have too...
I just currently got back in the field and I'm at the stage in my career when I need to amass a good tool collection. I'm wondering what the best quick/ratchet cutters and pipe wrenches are(I know about rigid). I just want the best bang for my buck. Thanks fellas!