1. The 7 Deadly Sins of Hand Soldering for Model Railroaders:
Not using clean (or new) parts. (Solderable parts solder best!)
Using too much flux. (Usually, the amount in the cored solder wire is all you need!)
Not selecting the correct iron tip, temperature, or solder wire size for the work.
Allowing movement between the parts during soldering.
Not supporting your hand holding the solder iron.
Not forming a correct heat bridge.
Moving the iron tip around during soldering. (Put it in one place and keep it there!)

2. Electronic Parts & Wire:
Digitrax Video:
“Soldering 2013”,
Tools:
Micro Mark Tools –
HMC Electronics –
Practical Tools -
Electronic Parts & Wire:
All Electronics Corp. -
Radio Shack –
Mouser Electronics –
Genie Garage Door Co. –
References:
MR, July 2003 – “The Lost Art of Soldering”
MR, February 2007 – “Ready, Set, Solder”
MR, May 2013 – “Soldering With Mr. H” by Neil Besougloff
MR, August 2013 – “The Art of Soldering” letter to the editor, David Carlton