ORIGINAL: Takedown
Deans are really easy to solder IMO. You just have to practice, practice, practice. I only apply solder to the spliced wire Im gonna solder to the deans plug and I dont put any solder on the deans plug. That way I know that the heatshrink will fit over the solder joint. I on the other hand I hate soldering two wires toghether because my soldering iron isnt all that great. I have hot & cold spots on my soldering iron so it sometimes makes it difficult to solder.
I put solder on both, in excess, then put the deans in a clamp, heat solder up on the plug until it is almost melting, put the wire on top of the plug, put the soldering iron above both and press down. Once the solder melts and the joint forms (a second or two), press down with the iron to minimize the space between the wire and the plug, remove the iron while holding the wire in place while the joint cools. Be sure to hold the wire about an inch back, otherwise you could burn yourself since the wire is a pretty good conductor of heat.
Another important thing is to use the right type of solder, good old fashioned lead rosin-core, not the newer tin/silver/copper stuff or whatever rohs compliant solder you can find. The new stuff is a disaster, you can end up with tin whiskers and other bad things happening down the line, it ends up causing more problems for the environment than it's worth.