Trouble soldering onto potentiometer tabs

I bought a small joystick that has two potentiometers attached to it. I had to solder wires onto the 3 tabs on each potentiometer, and had a devil of a time getting the solder to stick to the tabs.

I'm not the most skilled person with a soldering iron, and my iron is a poor one. Still, I have never had a problem like this. The solder sticks to the copper wires that I put through holes in the tabs and then twist to tighten. But the solder does not stick at all to the tabs.

I finally managed to get a workable join on each tab. But is there something I can do in such cases in the future? Does soldering flux help?

Yes flux helps. It also helps if you degrease the area with a little ISO. You should look into getting a flux pen. You can buy them from any of the electronics suppliers like Digikey ETC. You can also get it in small bottles with a needle tip. What you want is called rosin flux. If you have lots of pine trees around you can also make it.

Take a knife blade and scrape the surface oxidation, or whatever it is, off the
tabs until they're nice and shiny.

Thanks for the suggestions. I tried scraping the tabs, but there is not much there to scrap. Plus there seems to be no oxidation or anything like that. I can't tell what type of material they are made out of, but whatever it is, the material seems to hate solder. Solder just won't stick.

I have not had a chance to try flux yet. I hope to do that soon.

Sounds like the tabs aren't getting hot enough. Flux would help significantly.

What type of solder are you using? If the tabs are pre-tinned - then mixing no-lead and lead-based solder can be a problem (though the fact that you can't scrape them seems to indicate they aren't tinned). Also - are you sure you are applying enough heat to the tab? Proper heating is very important for good solder joints and proper wetting.