Citizen, if I can do it you can do it. Clean. All soldering, clean clean clean. If the pipes are in the house, make sure there's no water in them, doesn't matter if it is two floors away, it'll suck up your heat and screw the job. Drain them. Flux, they say don't use the acid kind it'll eat the joint in twenty years, okay, but still, use some sort of flux. It's part of that clean thing. Silver solder works a lot better than the cheap stuff, holds up under 250 psi steam so I like it but if you're a cheapskate, can try the crappy kind, will still melt nice.
Stick the joint together, heat it up with the propane torch, then touch the solder to an edge of the joint, it will suck right in and flow all around inside. Done. And looks pretty.
I'm guessing you're not doing the clean clean clean thing, maybe not getting the adjacent piping dry, probably using crap solder, no flux, and maybe not giving it enough heat. But them's the only ways you can screw up a copper pipe solder joint. It's actually easy.
Go practice, you'll see.