Clean the old solder off the iron then put a LITTLE flux on it.
(Most solders already have flux in them)
When it gets hot, touch the solder to it to "tin" (coat) it, then heat your work pieces until they are hot enough that the solder will flow as soon as you touch them.
In order to conduct heat properly, your soldering iron needs to be free of any old solder. After being exposed to air, it oxidizes and thus insulates against heat. We want heat to conduct so that we can apply everything quickly and efficiently. A dirty tip means that youll have to hold the iron on longer and risk heat damage to the PCB, and nobody wants that. Keep a wet sponge handy, and after the soldering iron is fully heated, softly scrape it against the sponge to remove old solder. The tip should be nice and shiny, or at least very close to it.
Next, were going to tin the tip. This will protect the tip and allow heat to conduct better via the presence of new solder. On the hot iron, carefully apply a small amount of fresh solder and coat the tip.
It should still be shiny if youve done it right. As soon as you tin the tip you should start soldering your components together. After every few joins, clean and re-tin, and again before putting your iron away into storage. This will really help increase the longevity of your tool. A good soldering iron should easily last years this way.
What kind of solder are you using? Is it rosin core, acid core or just solder. If it's just plain solder then you will need flux, if it is a cored solder then you don't need any flux. I'm a Amateur radio operator and have built and repaired my share of electronics with a soldering iron and rosin cored solder. Usually a wipe across a wet sponge will clean a soldering iron tip but if you used acid core solder then you may have to file the tip a little to expose the copper in the tip before you "tin" it again. As has already been said, you need to heat the work and not the solder but you do need some solder on the soldering iron tip so you can get a good heat transfer. Also if the tip is removable on the iron make sure it is tight or you will have heat transfer problems. If it's a soldering gun then make sure the set screws holding the tip are tight and the two probes that the tip is attached to aren't touching. This will short the gun out and the tip won't heat. If you are just soldering thin small copper then rosin core solder should be all you need and you don't have to worry about acid or flux damaging your tip. If you use anything other that rosin core you will need to clean the tip well with a wet cloth or sponge before turning the iron off and storing it for any length of time.
Hope this helps! I love soldering stuff and I love that rosin smell!
Wow! You all are a wealth of information. I purchased everything from the stained glass supply store in town, so it should all work together. I only used it for a few minutes, and I wiped it clean with a damp waffle weave towel. Its not dirty. I will try all of your great suggestions on Monday when the kids are back in school. Unfortunately can't play with it while they are home for safety reasons. I'm suspecting something wrong with the heating element in the tool, since its new. At least, I hope.