I did my first bit of soldering for a looooong time today, and just thought I'd share a couple of tips which helped me a lot.
Firstly, my newly-purchased soldering iron (an Antex one from Maplin) developed a blackened (i.e. oxidised) coating on the tip soon after starting to use it, which meant that it stopped working - i.e. it was impossible to "tin" the tip and it didn't heat things up properly. What solved that was a tin of tip tinner/cleaner from Maplin. Wiping the tip across that sorted it immediately.
Secondly, to give myself a "third hand", when holding the soldering iron in one hand, the solder in another, and wanting to also hold the wire still, I put an elastic band around the handles of a pair of pliers, and used this as a clamp to keep the wire still. Which worked well.