Very simple tip: veroboard and other copper-clad circuitboards are great for whacking together one-off projects but if you keep them stored, they can become hard to solder. This is particularly true if you’ve touched the copper. The problem is the oils in your skin help the copper oxidise and it won’t take solder as easily. That can lead to dry joints – solder joints that look like good joints but in fact aren’t joints at all.
The very simple solution is to run over it with a pencil eraser. I’ve used these Staedtler Mars Plastic pencil erasers will great success. They clean off dirt and oil and make it dead easy to create nice, smooth solder joints. Just be sure to brush away excess eraser rubbings off the copper before you solder and you should be as right as rain.