Soldering "non-fitting" pieces together

[hendecp]

OK, I hope I am not starting a thread that I can find answers somewhere else, or posting this in wrong forum. Anyhow, my question is around soldering copper together that is not on a joint. I am pretty "OK" soldering standard stuff and fittings together. But, when it comes to soldering a 1/4" tube into a hole that I drilled into a cap or side of a pipe (or any size for that matter) my work looks like sh*t! It usually holds up to leaks, but not always. What is the best way for accomplishing this? Is there a write up on this somewhere on this site? I have searched (not exhaustively) but have come up with not a bunch.

I have seen some pretty copper work on this site, so someone has the answers..... But, who is willing to share the secret?

Thanks in advance!