Here's a few things I've learned about basic soldering. I recommend you keep them in mind whenever you've got a soldering iron
in your hand;
The soldering iron needs to be hot enough. fine temperature control isn't necessary unless you solder extremely sensitive electronics. The most reliable way to apply too much heat to whatever you're soldering is to hold an almost-hot-enough iron on the components for too long.
The tip of your soldering iron is covered with a special coating. This makes it easier for the iron to break the surface tension on the solder. never file off the tip for whatever reason. I guarantee you the tip will be ruined. If you feel the tip isn't pointy enough or what have you, replace it.
Do not use the soldering iron to melt the solder on the tip and then apply it. The cold components will reject the solder and the joint will be a failure. Usually you can recognize a joint where the components weren't hot enough by observing the color. A proper joint should have a mirrorlike surface, a bad one will be dull and maybe have a hint of white.
Throw the old solder your dad has lying around away. The same goes for that 400W iron. They weren't made with today's electronics in mind and will make your task well nigh impossible. Unless you're soldering large pieces of metal together of course.
A soldering iron is cheap, and the same goes for solder. Get an iron with a pointy tip(they're standard anyway) and some standard issue solder. All solder bought at your local electronics pusher will have a rosin core and propably also a small amount of silver, so don't worry about it. Never mind a temperature control; if you're reading this chances are, you're not at the stage where you need it, and it'll probably be years before you will.
Other tools that are insanely great to have are diagonal cutters, a third hand (but in a lot of cases a pair of pliers with a rubber band around the handles will do nicely) and maybe something to suck up solder when you make a mistake. I can recommend getting a solder sucker that uses a spring to create suction. They're also very cheap. You can also get rolls of braided copper wire that can suck up solder through capillary action. These are more precise, but not as fast as the springloaded sucker.
Now, the proper way to go about soldering something is like this:
Turn on your soldering iron. Go out into the kitchen(or bathroom) and wet your sponge. Did I mention the sponge? Get a sponge, they're cheap and a lot better than using a newspaper. Squeeze the sponge so it's moist and not wet. A dry sponge is worthless.
In the meantime the soldering iron should be hot enough to work with. The first thing you do is melt some solder on the tip of the iron, then wipe it off on the sponge. This can't be done properly with a newspaper(neener) since it won't remove the solder from the iron. This leaves a fine coating on the tip that will make the solder melt more readily. It also preserves the coating.
Now, are you certain that you're about to make the right connection? It's always annoying (and a little painful) to undo your masterpiece.
In the case that you're soldering a plug onto a cable, strip the appropriate wires, and remember to pull that lille cap that is supposed to screw onto the plug when you're done soldering onto the cable. I can't speak for others, but this is the most common mistake I make.
If you're soldering something involving wires you need to apply some solder to the wires before attaching them to anything. Copper is an insanely good heat conductor (but you always had a suspicion about that, didn't you?), and it'll steal the heat from the joint you're trying to make until the insulator melts forcing you to drop the wire and invent new curse words.
As I said earlier, you need to heat the components you're making the connection between and not just the solder.
However, I can recommend placing the tip of the iron on the joint between the components, then applying the solder on the place where the iron meets the joint. I always use this technique because it makes for fast soldering and is easy to deal with. The trick is that the components don't have to be hot enough to melt the solder, just somewhat warm. In the case of larger items such as XLR plugs, the solder will probably melt some time before it actually connects with the leads on the plugs because they take some time heating up. Until then the solder will form a globule attached to the tip of the iron. If the iron isn't hot enough to warm up the plug as well as melting the solder, you will end up with a very hot plug because you'll have to apply heat for too long.
Therefore, either take short breaks between bouts of heavy soldering or use a more powerful iron. If I need to solder large plugs I usually crank up the temperature control so I can draw on the temperature capacity of the tip.
There are other types of equipment for soldering, but I only recommend them for highly specialized purpuses;
there are soldering irons which have a small rubber bulb attached at the tip. Through squeezing and releasing the bulb you can suck solder away. I've never used this device and can't say anything about its benefits and deficits.
You can also buy soldering irons that run on propane and butane. As you propably suspect they're cool, expensive and heat up rapidly. They can be fitted with various heads so you for instance can use them for blasting hot air on that heat shrink tubing you've used for insulating your connections.
There. That's about all there is to it. If you follow my guide you should be able to become one with the soldering gods in a small amount of time.