Tips on Soldering

1. Replace tip if necessary - I don't do this very often but some cheap soldering irons can ware out over only a few weeks of use. You will know if you need to replace your tip because it will look disfigured almost like it melted.
2. Clean the tip with a sponge - do this while the soldering iron is hot. Simply use a damp sponge to wipe  away any carbon (black) and excess solder. The result will be a nice shiny tip.
3. Soldering paste or flux can be used to help solder attach to some surfaces but this is not always necessary.
4. Make sure you are using good solder. Some solder contains impurities and may not bond well to the materials that you are using. I have had good luck with 60/40.