Since most of my soldering is on larger connections, such as valve equipment, I use a larger soldering iron of 65 watts. If I use a smaller one, the bigger metal traces, or metal chassis absorb the heat, and my solder doesn't melt.
It is a temperature variable one, so I can dial it back for SMD soldering and such. I've had it since I was 10, so I don't know any better than this one. There could be better ones out there!
Also, keep the tip of the iron clean! Get a damp sponge to brush the tip on when you're done.
YouTube should have plenty of informative tutorials to help too.
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